Biological and clinical insights from genetics of insomnia symptoms

Insomnia Associated With Increased Risk of Atopic Dermatitis: A Two-Sample Mendelian Randomization Study

BACKGROUND

The causal relationships between sleep traits and allergic diseases remain unclear. This study sought to explore their causal associations using Mendelian randomization (MR) analysis.

METHODS

This study utilized summary-level data from genome-wide association studies (GWAS) and selected genetic variants associated with sleep traits as instrumental variables (IVs). For the primary analysis, the inverse-variance weighted (IVW) method was utilized. To further evaluate causal effects, we applied weighted median, weighted mode, and MR-Egger regression. Sensitivity analyses, such as linkage disequilibrium score (LDSC) regression, MR-Egger regression, Cochran's Q test, leave-one-out analysis, and MR-PRESSO, were carried out to confirm result robustness.

RESULTS

IVW analysis revealed that genetically predicted insomnia was causally associated with a higher risk of atopic dermatitis (OR = 1.79, 95% CI: 1.17-2.74, P = 0.01), and preferring an evening chronotype was causally associated with a lower risk of allergic rhinitis (IVW: OR = 0.99, 95% CI: 0.99-1.00, P = 0.02). The LDSC analysis further identified a significant genetic correlation between insomnia and atopic dermatitis (rg = 0.107, P = 0.039), but not between chronotype and allergic rhinitis (rg = -0.036, P = 0.339). No significant connections were identified between other sleep traits and allergic diseases. The MR-Egger intercept test did not indicate pleiotropy, except for the association with allergic asthma.

CONCLUSION

Chronotype and insomnia were causally associated with the efficacy of sleep-based interventions in allergic disease management.

Identifying links between cardiovascular disease and insomnia by modeling genes from a pleiotropic locus

Insomnia symptoms double the risk of cardiovascular disease (CVD), yet shared genetic pathways remain unclear. Genome-wide association studies identified a genetic locus (near ATP5G1, UBE2Z, SNF8, IGF2BP1 and GIP) linked to insomnia and CVD. We used Drosophila models to perform tissue-specific RNA interference knockdowns of four conserved orthologs (ATPsynC, lsn, Bruce and Imp) in neurons and the heart. Neuronal-specific knockdown of ATPsynC, Imp and lsn impaired sleep quantity and quality. In contrast, cardiac knockdown of ATPsynC and lsn reduced cardiac function and lifespan, with lsn knockdown also causing cardiac dilation and myofibrillar disorganization. Cross-tissue effects were evident: neuronal Imp knockdown compromised cardiac function, whereas cardiac ATPsynC and lsn knockdown increased sleep fragmentation and inflammation (marked by Upd3 elevation in the heart or head). Overexpression of Upd3 in neurons impaired cardiac function, and its overexpression in the heart disrupted sleep. Our findings reveal conserved genes mediating tissue-specific and cross-tissue interactions between sleep and cardiac function, providing novel insights into the genetic mechanisms linking insomnia and CVD through inflammation.

Characterizing Genetic-Predisposed Proteins Involving Insomnia by Integrating Genome-Wide Association Study Summary Statistics

Large case-control genome-wide association studies (GWASs) have detected loci associated with insomnia, but how these risk loci confer disease risk remains largely unknown. By integrating brain protein quantitative trait loci (pQTL) (NpQTL1 = 376, NpQTL2 = 152) and expression QTL (eQTL) (N = 452) datasets, with the latest insomnia GWAS summary statistics (Ncase = 109,548, NControls = 277440), we conducted proteome/transcriptome-wide association study (PWAS/TWAS) and Mendelian randomization (MR) analysis, aiming to identify causal proteins involving in the pathogenesis of insomnia. We also explored the bi-directional causality between insomnia and several common diseases. As a result, the altered protein level of 28 genes in the brain was associated with the risk of insomnia in the discovery stage of PWAS, of which 18 genes' associations were replicated in the confirmatory stage of PWAS. Among them, four proteins (2-aminoethanethiol dioxygenase (ADO), calcium-modulating cyclophilin ligand (CAMLG), islet cell autoantigen 1 like (ICA1L) and latexin (LXN)) were found to be the most likely causal genes for insomnia with validations from TWAS, MR, and colocalization results. Specifically, the higher protein level of ADO, CALMG, and ICA1L was causally associated with a lower risk of insomnia. In comparison, the higher protein level of LXN was causally associated with an increased risk for insomnia. Moreover, genetically predicted insomnia was causally associated with an increased risk of developing cardiovascular diseases and depression. In conclusion, our study identified ADO, CAMLG, ICA1L, and LXN as potentially causal proteins in the pathogenesis of insomnia. This could provide insights into further mechanistic studies and therapeutic development for insomnia.

Exploring the Relationship Between Obstructive Sleep Apnea and Olfactory Function

Obstructive sleep apnea (OSA) is increasingly recognized as a chronic condition that is closely interrelated to olfactory disorders, with a significant contribution to quality of health and overall quality of life. This narrative review aims to provide a thorough overview of the emerging evidence that now integrates these two previously considered distinct physiologic systems. Studies published recently have reported a significantly higher frequency of olfactory dysfunction among OSA patients compared to the general population, which raises the possibility of a causal relationship. We explore the postulated mechanisms behind this association, namely, the chronic intermittent hypoxia, local inflammatory effect, and neuroanatomical changes attributed to OSA. The review further explores the clinical impacts of this relationship through proposing the potential for an olfactory assessment to be used as a diagnostic modality for OSA and the effects of OSA treatment on olfactory function. Thus, we explore the difficulties in treating patients who experience both and suggest future areas for research. This review attempts to bridge the gap between the existing literature and impending investigation necessary for a better management of the interaction of sleep apnea and the human sense of smell.

Mendelian randomization study of sleep traits and risk of colorectal cancer

A potential association of endogenous circadian rhythm disruption with risk of cancer development has been suggested, however, epidemiological evidence for the association of sleep traits with colorectal cancer (CRC) is limited and often contradictory. Here we investigated whether genetically predicted chronotype, insomnia and sleep duration are associated with CRC risk in males, females and overall and according to CRC anatomical subsites using Mendelian randomization (MR). The two-sample inverse variance weighted (IVW) method was applied using summary-level data in up to 58,221 CRC cases and 67,694 controls and genome-wide association data of genetic variants for self-reported sleep traits. Secondary analyses using alternative instruments and sensitivity analyses assessing potential violations of MR assumptions were conducted. Genetically predicted morning preference was associated with 13% lower risk of CRC in men (ORIVW = 0.87, 95% CI = 0.78, 0.97, P = 0.01), but not in women or in both sexes combined. Τhis association remained consistent in some, but not all, sensitivity analyses and was very similar for colon and rectal cancer. There was no evidence of an association for any other sleep trait. Overall, this study provides little to no evidence of an association between genetically predicted sleep traits and CRC risk.

Research hotspots and frontier analysis on Mendelian randomization in osteoporosis-related fields: A review based on bibliometric and visual analysis

This research seeks to thoroughly examine the present state and research hotspots in Mendelian randomization (MR) in osteoporosis (OP)-related fields, providing a reference for future research directions in this area. Following an exhaustive search of the Web of Science Core Collection database, our analysis utilized citation statistics for osteoporosis studies conducted from January 1, 2007, through March 15, 2024. Bibliometric and visual analyses were conducted using two online analysis systems, CiteSpace and VOSviewer. The analysis included a variety of dimensions, including the distribution of citations, authorship, published journals, year of publication, countries, co-occurrence keywords and keyword clustering. From 2007 to 2024, the number of publications in MR in OP-related fields showed an overall increased. High-impact publications and leading contributors were primarily from China, followed by the USA and England. The journal with the largest number of publications in MR in OP-related fields is the Journal of Bone and Mineral Research. Risk factor research, genome-wide associations, meta-analysis, fractures, and gene loci were the main research hotspots. Interdisciplinary integration, MR research combined with data from clinical trials and observational studies, represents the future development trend. Research on MR in OP-related fields has mainly been conducted in China, the USA, and England. The research hotspots were aimed at exploring the causative between risk factors and OP. Future studies are likely to center on multidisciplinary integration.

Drosophila Modeling Identifies Increased Sleep as a Link Between Insomnia and Cardiovascular Disease

Insomnia is a common sleep disorder associated with negative long-term health outcomes. Mendelian randomization studies have found that insomnia significantly increases the risk of cardiovascular disease (CVD). To better understand the link between sleep and heart health, we identify genes associated with both insomnia and CVD. We model the disruption of the Drosophila melanogaster orthologs in neurons and cardiac tissue to characterize their cell-autonomous and non-cell-autonomous role in regulating sleep and cardiac physiology. We identify three genes that function in neurons and the heart to cell-autonomously regulate the function of each tissue. We find that the disruption of insomnia- and CVD-associated Drosophila orthologs in the heart most often lead to increased nighttime sleep. Inversely, disruptions in neurons that lead to increased sleep most often result in an elevated heart rate. To confirm the association between increased sleep and cardiac function, we performed a genetic correlation analysis from human data between long sleep-related traits and adverse cardiac outcomes. Significant correlations were found between most long sleep traits and heart failure, coronary artery disease, or myocardial infarction, reinforcing our findings in the fly linking increased or excessive sleep and altered cardiac health.

Genomic dissection of sleep archetypes in a large autism cohort

Poor sleep is a major concern among individuals with autism and their caregivers. To better characterize the genetic and phenotypic heterogeneity of poor sleep in autism, we recruited 5,686 families from SPARK, a nationwide genetic study of autism, who described their sleep experiences using the Children's Sleep Health Questionnaire (CSHQ) and other self-report items. The collective experiences from this large sample allowed us to discover eight distinct archetypes of sleep in autism. Membership in some of these archetypes showed significant SNP-heritability (0.50 - 0.65, 95% confidence interval = 0.08 - 1), and polygenic estimates of educational attainment, BMI, and ADHD risk contributed extensively to the genetic signatures of these sleep archetypes. Surprisingly, polygenic estimates of general population sleep phenotypes showed sparser and more modest associations, perhaps suggesting that the genetic drivers of disordered sleep in autism may be distinct from those encountered in the general population. GWAS on archetype membership yielded no genome-wide significant loci, however, the most significant gene for the most severe archetype was the nitric oxide (NO) signaling gene NOS1AP, which was previously linked to sleep disruption in schizophrenia. Finally, the eight sleep archetypes showed specific signatures of treatment response across five major categories of sleep aid, pointing to the potential of treatment plans that are tailored to the nature of the sleep problem. These findings provide critical new insight into the comorbidities, subtypes, and genetic risk factors associated with disordered sleep in autism.

Efficient and accurate framework for genome-wide gene-environment interaction analysis in large-scale biobanks

Gene-environment interaction (G×E) analysis elucidates the interplay between genetic and environmental factors. Genome-wide association studies (GWAS) have expanded to encompass complex traits like time-to-event and ordinal traits, which provide richer phenotypic information. However, most existing scalable approaches focus only on quantitative or binary traits. Here we propose SPAGxECCT, a scalable and accurate framework for diverse trait types. SPAGxECCT fits a genotype-independent model and employs a hybrid strategy including saddlepoint approximation (SPA) for accurate p value calculation, especially for low-frequency variants and unbalanced phenotypic distributions. We extend SPAGxECCT to SPAGxEmixCCT, which accounts for population stratification and is applicable to multi-ancestry or admixed populations. SPAGxEmixCCT can further be extended to SPAGxEmixCCT-local, which identifies ancestry-specific G×E effects using local ancestry. Through extensive simulations and real data analyses of UK Biobank data, we demonstrate that SPAGxECCT and SPAGxEmixCCT are scalable to analyze large-scale study cohort, control type I error rates effectively, and maintain power.

The interplay between genomic copy number variants, sleep, and cognition in the general population

Genomic Copy Number variants (CNVs) increase risk for neurodevelopmental disorders (NDDs) and affect cognition, but their impact on sleep remains understudied despite the well-established link between sleep disturbances, NDDs, and cognition. We investigated the relationship between CNVs, sleep traits, cognitive ability, and executive function in 498,852 individuals from an unselected population in the UK Biobank. We replicated the U-shape relationship between measures of cognitive ability and sleep duration. The effects of CNVs on sleep duration were evident at the genome-wide level; CNV-burden analyses showed that overall, CNVs with an increasing number of intolerant genes were associated with increased or decreased sleep duration in a U-shape pattern (p < 2e-16), but did not increase risk of insomnia. Sleep duration only marginally mediated the robust association between CNVs and poorer cognitive performance, suggesting that sleep and cognitive phenotypes may result from pleiotropic effects of CNVs with minimal causal relationship.

Association of sleep quality and its change with the risk of depression in middle-aged and elderly people: A 10-year cohort study from England

BACKGROUND

Persistently poor sleep quality in young adults is linked to a higher risk of depression. However, the impact of changes in sleep quality on depression risk in middle-aged and older adults remain unclear. This study investigates the association between sleep quality, its changes, and the risk of depression in middle-aged and elderly people.

METHODS

We included 4007 participants (mean age 63.0 ± 7.6 years, 53.0 % women) from the English Longitudinal Study of Ageing. Sleep quality was assessed using the Jenkins Sleep Problems Scale and a global sleep quality question. Depression was evaluated with the Center for Epidemiological Studies Depression Scale and self-reported doctor-diagnosed depression. Multivariable logistic regression, restricted cubic spline curve, and mediation analysis was employed.

RESULTS

After 10 years of follow-up, 777 individuals developed depression. Sleep quality scores positively correlated with depression risk. Among those with good sleep quality, worsening sleep quality increased depression risk (OR = 1.67, 95 % CI: 1.21-2.31). For those with intermediate sleep quality, improved sleep quality reduced depression risk (OR = 0.70, 95 % CI: 0.50-0.98). Conversely, worsening sleep quality increased depression risk (OR = 2.11, 95 % CI: 1.47-3.02). Pain and functional disability partially mediated the association between intermediate/poor sleep quality and depression (9.8 % and 4.2 %, respectively).

LIMITATIONS

Sleep quality is based on self-reported.

CONCLUSIONS

Intermediate, poor, and worsening sleep quality are linked to higher depression risk. Improving sleep quality mitigates depression risk in those with intermediate sleep quality. Sleep quality may influence depression indirectly through pain and functional disability.

Investigating the impact of multidimensional sleep traits on cardiovascular diseases and the mediating role of depression

BACKGROUND

Observational studies have reported that sleep is associated with the risk of major depressive disorder (MDD) and cardiovascular diseases (CVDs). However, the causal relationships among various sleep traits remain contentious, and whether MDD mediates the impact of specific sleep traits on CVDs is unclear.

METHODS

We performed two-sample Mendelian randomisation analyses to explore whether insomnia, sleep time, daytime napping, daytime sleepiness, chronotype, snoring or obstructive sleep apnoea were causally associated with the risk of five CVDs, including coronary artery disease (CAD), myocardial infarction (MI), heart failure (HF), atrial fibrillation and stroke. Mediation analyses were performed to assess the proportion mediated by MDD.

RESULTS

Genetically predicted insomnia, short sleep, daytime napping and daytime sleepiness increased the risk of CVDs, with the OR ranging from 1.24 (95% CI 1.06 to 1.45) for insomnia on stroke to 1.55 (95% CI 1.28 to 1.89) for insomnia on MI. In contrast to short sleep, genetically predicted sleep duration decreased the risk of CAD (OR 0.88 (95% CI 0.80 to 0.97)), MI (OR 0.89 (95% CI 0.80 to 0.99)) and HF (OR 0.90 (95% CI 0.83 to 0.98)). However, we found no significant associations of long sleep, chronotype, snoring and obstructive sleep apnoea with increased risk for any CVD subtype. Additionally, the effect of insomnia was partially mediated by MDD for the risk of CAD (proportion mediated: 8.81% (95% CI 1.20% to 16.43%)), MI (9.17% (95% CI 1.71% to 16.63%)) and HF (14.46% (95% CI 3.48% to 25.45%)). Similarly, the effect of short sleep was partially mediated by MDD for the risk of CAD (8.92% (95% CI 0.87% to 16.97%)), MI (11.43% (95% CI 0.28% to 22.57%)) and HF (12.65% (95% CI 1.35% to 23.96%)). MDD also partially mediated the causal effects of insomnia on stroke, sleep duration on CAD, MI and HF, daytime napping on HF and daytime sleepiness on CAD.

CONCLUSIONS

Our study provides evidence that genetically predicted insomnia, short sleep, frequent daytime napping and sleepiness are associated with a higher risk of certain CVD subtypes, partly mediated by MDD.

Identifying Risk and Protective Factors for Shift Work Sleep Disorder: Insights from UK Biobank Night Shift Workers

Shift Work Sleep Disorder (SWSD) is a significant and highly prevalent condition affecting up to 48% of individuals with irregular work schedules. The diagnostic criteria for SWSD include persistent insomnia or sleepiness in relation to shift work, not attributable to other disorders or external factors. To explore risk factors of SWSD, we conducted a cross-sectional analysis among 10,787 night shift workers in the UK Biobank. To determine correlates of SWSD using multivariable-adjusted logistic regression models, a preselection of potential risk factors was made on the basis of previous literature. Self-identifying as 'Asian or Asian British' or 'Black or Black British' (compared to being 'White'), male sex, and high scores on sociability, warmth and diligence were associated with lower odds for SWSD. We did not find significant associations of chronotype, frequency of alcohol intake, smoking, and time employed in current job with SWSD. These findings underscore the need for targeted interventions and workplace policies to mitigate the adverse effects of SWSD. Future research should aim to explore the mechanisms behind these associations and develop strategies to enhance shift work tolerance among night shift workers.

Sleep traits causally affect epigenetic age acceleration: a Mendelian randomization study

Sleep disorders (SDs) are a common issue in the elderly. Epigenetic clocks based on DNA methylation (DNAm) are now considered highly accurate predictors of the aging process and are associated with age-related diseases. This study aimed to investigate the causal relationship between sleep traits and the epigenetic clock using Mendelian randomization (MR) analysis. The genome-wide association study (GWAS) statistics for epigenetic clocks (HannumAge, intrinsic epigenetic age acceleration [IEAA], PhenoAge, and GrimAge) and sleep traits were obtained from the UK Biobank (UKB), 23andMe and Finngen. Moreover, crucial instrumental variables (IVs) were evaluated. Inverse variance weighted (IVW), MR-Egger, weighted median (WM), weighted mode, and simple mode methods were employed to assess the causal relationship between them. Multiple analyses were performed for quality control evaluation. Our study showed that self-reported insomnia may speed up the aging process by GrimAge clock, while GrimAge acceleration could faintly reduce self-reported insomnia. Epigenetic clocks mainly influence sleep traits by PhenoAge and GrimAge with weak effects. This may indicate that early interventions of SDs could be a breaking point for aging and age-related diseases. Further studies are required to elucidate the potential mechanisms involved.

Multifactorial influences on childhood insomnia: Genetic, socioeconomic, brain development and psychopathology insights

Insomnia is the most prevalent sleep disturbance during childhood and can result in extensively detrimental effects. Children's insomnia involves a complex interplay of biological, neurodevelopmental, social-environmental, and behavioral variables, yet remains insufficiently addressed. This study aimed to investigate the multifactorial etiology of childhood insomnia from its genetic architecture and social-environmental variables to its neural instantiation and the relationship to mental health. This cohort study uses 4340 participants at baseline and 2717 participants at 2-year follow-up from the Adolescent Brain Cognitive Development (ABCD) Study. We assessed the joint effects of polygenic risk score (PRS) and socioeconomic status (SES) on insomnia symptoms and then investigated the underlying neurodevelopmental mechanisms. Structural equation model (SEM) was applied to investigate the directional relationships among these variables. SES and PRS affected children's insomnia symptoms independently and additively (SES: β = -0.089, P = 1.91 × 10-8; PRS: β = 0.041, P = 0.008), which was further indirectly mediated by the deviation of inferior precentral sulcus (β = 0.0027, P = 0.0071). SEM revealed that insomnia (β = 0.457, P < 0.001) and precentral development (β = -0.039, P = 0.009) significantly mediated the effect of SES_PRS (accumulated risks of PRS and SES) on psychopathology symptoms. Furthermore, baseline insomnia symptoms, SES_PRS, and precentral deviation significantly predicted individual total psychopathology syndromes (r = 0.346, P < 0.001). These findings suggest the additive effects of genetic and socioenvironmental factors on childhood insomnia via precentral development and highlight potential targets in early detection and intervention for childhood insomnia.

Emotional Processing Following Digital Cognitive Behavioral Therapy for Insomnia in People With Depressive Symptoms: A Randomized Clinical Trial

Importance

Cognitive behavioral therapy for insomnia (CBT-I) has been shown to reduce depressive symptoms, but the underlying mechanisms are not well understood and warrant further examination.

Objective

To investigate whether CBT-I modifies negative bias in the perception of emotional facial expressions and whether such changes mediate improvement in depressive symptoms.

Design, Setting, and Participants

A randomized clinical trial of digital CBT-I vs sleep hygiene education was conducted. Adults living in the UK who met diagnostic criteria for insomnia disorder and Patient Health Questionnaire-9 criteria (score ≥10) for depression were recruited online from the community and randomly assigned to either a 6-session digital CBT-I program or a sleep hygiene webpage. Participant recruitment took place between April 26, 2021, and January 24, 2022, and outcomes were assessed at 5 and 10 weeks post randomization. Data analysis was performed from December 1, 2022, to March 1, 2023.

Main Outcomes and Measures

Coprimary outcomes were recognition accuracy (percentage) of happy and sad facial expressions at 10 weeks assessed with the facial expression recognition task. Secondary outcomes were self-reported measures of insomnia, depressive symptoms, affect, emotional regulation difficulties, worry, perseverative thinking, midpoint of sleep, social jet lag, and the categorization of and recognition memory for emotional words. Intention-to-treat analysis was used.

Results

A total of 205 participants were randomly assigned to CBT-I (n = 101) or sleep hygiene education (n = 104). The sample had a mean (SD) age of 49.3 (10.1) years and was predominately female (165 [80.8%]). Retention was 85.7% (n = 175). At 10 weeks, the estimated adjusted mean difference for recognition accuracy was 3.01 (97.5% CI, -1.67 to 7.69; P = .15; Cohen d = 0.24) for happy facial expressions and -0.54 (97.5% CI, -3.92 to 2.84; P = .72; Cohen d = -0.05) for sad facial expressions. At 10 weeks, CBT-I compared with control decreased insomnia severity (adjusted difference, -4.27; 95% CI, -5.67 to -2.87), depressive symptoms (adjusted difference, -3.91; 95% CI, -5.20 to -2.62), negative affect (adjusted difference, -2.75; 95% CI, -4.58 to -0.92), emotional regulation difficulties (adjusted difference, -5.96; 95% CI, -10.61 to -1.31), worry (adjusted difference, -8.07; 95% CI, -11.81 to -4.33), and perseverative thinking (adjusted difference, -4.21; 95% CI, -7.03 to -1.39) and increased positive affect (adjusted difference, 4.99; 95% CI, 3.13-6.85). Improvement in negative affect, emotional regulation difficulties, and worry at week 5 mediated the effect of CBT-I on depression severity at 10 weeks (% mediated: 21.9% Emotion regulation difficulties; 24.4% Worry; and 29.7% Negative affect). No serious adverse events were reported to the trial team.

Conclusions and Relevance

This randomized clinical trial did not find evidence that CBT-I engenders change in the perception of facial expressions at post treatment, despite improvements in insomnia and depressive symptoms. Early change in negative affect, emotional regulation difficulties, and worry mediated lagged depression outcomes and deserve further empirical scrutiny.

Trial Registration

isrctn.org Identifier: ISRCTN17117237.

Genetic evidence of the causal relationships between psychiatric disorders and cardiovascular diseases

OBJECTIVE

Our primary objective is to investigate the causal relationships between 12 psychiatric disorders (PDs) and atrial fibrillation (AF), coronary artery disease (CAD), myocardial infarction (MI), and heart failure (HF).

METHODS

Firstly, we used linkage disequilibrium score regression to calculate the genetic correlations between 12 PDs and 4 cardiovascular diseases (CVDs). Subsequently, we performed two-sample and bidirectional Mendelian randomization (MR) analyses of phenotypes with significant genetic correlations to explore the causal relationships between PDs and CVDs. Inverse variance weighted with modified weights (MW-IVW), Robust Adjusted Profile Score, Inverse Variance Weighted, weighted median and weighted mode were used to evaluate causal effects, with MW-IVW being the main analysis method. And to validate the MR results, we conducted the replicate analyses using data from the FinnGen database.

RESULTS

Conducting MR analyses in phenotypes with significant genetic correlations, we identified bidirectional causal relationships between depression (DEP) and MI (DEP as exposure: OR = 1.1324, 95 % confidence interval (CI): 1.0984-1.1663, P < 0.0001; MI as exposure: OR = 1.0268, 95 % CI: 1.0160-1.0375, P < 0.0001). Similar relationships were observed in Attention Deficit/Hyperactivity Disorder (ADHD) and HF (ADHD as exposure: OR = 1.0270, 95 % CI: 1.0144-1.0395, P < 0.0001; HF as exposure: OR = 1.0980, 95 % CI: 1.0502-1.1458, P < 0.0001).

CONCLUSIONS

In our study, we conducted the comprehensive analyses between 12 PDs and CVDs. By bidirectional MR analysis, we observed significant causal relationships between MI and DEP, HF and ADHD. These findings suggest possible complex causal relationships between PDs and CVDs.

Impact of sleep characteristics on IVF/ICSI outcomes: A prospective cohort study

BACKGROUND

Infertility affects millions of individuals worldwide, imposing significant personal and societal burdens. Assisted reproductive technologies (ART), such as IVF and ICSI, provide hope for many, yet clinical pregnancy rate per embryo transfer remains around 35 %. Modifiable lifestyle factors, including sleep, may influence ART outcomes. However, the relationship between specific sleep characteristics and IVF/ICSI success is unclear. This study aims to explore the associations between sleep characteristics and various IVF/ICSI outcomes. Additionally, we investigated if perceived stress mediates these relationships.

METHODS

This prospective cohort study enrolled 174 women undergoing IVF/ICSI at Zhongnan Hospital of Wuhan University from December 2021 to December 2023. Prior to initial ART treatment, participants completed the Pittsburgh Sleep Quality Index (PSQI) and the Perceived Stress Scale (PSS-10). IVF/ICSI outcomes such as the number of retrieved oocytes, matured oocytes, number of fertilized oocytes, fertilization rate, good-quality embryos, blastocyst formation rate and early pregnancy outcome (implantation and clinical pregnancy) were obtained from medical records. We employed multivariate generalized linear models to assess the associations between sleep characteristics and IVF/ICSI outcomes. Dose-response relationships between napping duration and maturation rate were analyzed using generalized additive models. Mediation analysis was used to assess the role of stress in the relationship between sleep characteristics and IVF/ICSI outcomes.

RESULTS

Women reporting poor sleep quality had significantly fewer retrieved oocytes (-22.89 %, 95%CI: 37.82 %, -4.00 %) and matured oocytes (-22.01 %, 95%CI: 37.54 %, -2.62 %). Those sleeping ≥10 h per night had fewer retrieved oocytes (-30.68 %, 95%CI: 48.88 %, -6.00 %), matured oocytes (-27.17 %, 95%CI: 46.57 %, -0.73 %), and good-quality embryos (-45.64 %, 95%CI: 65.43 %, -14.51 %). Women experiencing difficulty falling asleep more than three times a week had a significant reduction in blastocyst rates (-64.40 %, 95 % CI: 85.55 %, -12.30 %). Those reporting difficulty falling asleep less than once a week had fewer retrieved oocytes (-28.89 %, 95%CI: 47.34 %, -3.98 %), and matured oocytes (-27.77 %, 95%CI: 46.90 %, -1.73 %). Napping exceeding 1 h daily was associated with a significantly lower oocyte maturation rate (-73.8 %, 95%CI: 88.91 %, -38.06 %). A significant non-linear dose-response relationship was observed between napping duration and maturation rate (p < 0.001), with maturation rates initially increasing slightly with short naps but declining significantly with longer naps, particularly beyond 1 h. This relationship was significant among women with good sleep quality (PSQI ≤5) (p < 0.001) and those with normal BMI (p = 0.0005). Perceived stress did not significantly mediate these associations.

CONCLUSION

Our findings suggest that sleep characteristics, particularly poor quality, difficulty falling asleep, long sleep durations, negatively impact various IVF/ICSI outcomes. Longer daytime napping is inversely associated with oocyte maturation rates, especially among women with good sleep quality and normal BMI. Perceived stress did not appear to influence the relationship between sleep and IVF outcome. While optimizing sleep patterns may hold promise for improving IVF/ICSI success rates, it is essential to approach lifestyle guidance with caution, given the current limitations in confirming causative roles. Further studies are needed to clarify the extent and nature of the relationship between sleep characteristics and IVF/ICSI outcomes.

Exploring the link between comorbid insomnia and sleep apnea (COMISA) and erectile dysfunction: implications for male sexual health

INTRODUCTION

This review explores the interplay between comorbid insomnia and sleep apnea (COMISA) and erectile dysfunction (ED), 2 conditions that significantly impact men's health. COMISA, a recently recognized condition characterized by the coexistence of insomnia and obstructive sleep apnea, has been shown to disrupt sleep architecture and cause intermittent hypoxia. These disturbances are increasingly linked to the exacerbation of ED, a prevalent issue among men. Understanding the connection between COMISA and ED is crucial for developing integrated treatment approaches that address both sleep and sexual health.

OBJECTIVES

We aim to explore the epidemiological, physiological, and potential therapeutic intersections of COMISA and ED. This review sets out to develop a better understanding of the relationship between these conditions and to emphasize the need for an integrated diagnostic and therapeutic approach that addresses both sleep and sexual health.

METHODS

Through a comprehensive analysis, including a detailed examination of extant studies, we address the hormonal imbalances and alterations in neural pathways that collectively contribute to the complex pathophysiology of ED and how these are particularly susceptible to the concurrent presence of COMISA.

RESULTS

Our analysis indicates that disruptions in sleep architecture and intermittent hypoxia associated with COMISA can exacerbate ED. Hormonal imbalances, endothelial dysfunction, autonomic imbalance, and increased inflammation and oxidative stress are key mechanisms through which COMISA influences ED. These factors collectively impair vascular health, reduce testosterone levels, disrupt neural control of erections, and contribute to the severity of ED.

CONCLUSIONS

This review underscores the necessity for an integrated approach to diagnosis and therapy that considers both sleep and sexual health to improve overall outcomes. These insights should foster a deeper understanding of the relationship between COMISA and ED, encourage further research in this area, and potentially lead to the development of innovative treatment strategies to manage these closely intertwined health concerns.

Genetic associations between orexin genes and phenotypes related to behavioral regulation in humans, including substance use

The hypothalamic neuropeptide system of orexin (hypocretin) neurons provides projections throughout the neuraxis and has been linked to sleep regulation, feeding and motivation for salient rewards including drugs of abuse. However, relatively little has been done to examine genes associated with orexin signaling and specific behavioral phenotypes in humans. Here, we tested for association of twenty-seven genes involved in orexin signaling with behavioral phenotypes in humans. We tested the full gene set, functional subsets, and individual genes involved in orexin signaling. Our primary phenotype of interest was Externalizing, a composite factor comprised of behaviors and disorders associated with reward-seeking, motivation, and behavioral regulation. We also tested for association with additional phenotypes that have been related to orexin regulation in model organism studies, including alcohol consumption, problematic alcohol use, daytime sleepiness, insomnia, cigarettes per day, smoking initiation, and body mass index. The composite set of 27 genes corresponding to orexin function was highly associated with Externalizing, as well as with alcohol consumption, insomnia, cigarettes per day, smoking initiation and BMI. In addition, all gene subsets (except the OXR2/HCRTR2 subset) were associated with Externalizing. BMI was significantly associated with all gene subsets. The "validated factors for PPOX/HCRT" and "PPOX/HCRT upregulation" gene subsets also were associated with alcohol consumption. Individually, 8 genes showed a strong association with Externalizing, 12 with BMI, 7 with smoking initiation, 3 with alcohol consumption, and 2 with problematic alcohol use, after correction for multiple testing. This study indicates that orexin genes are associated with multiple behaviors and disorders related to self-regulation in humans. This is consistent with prior work in animals that implicated orexin signaling in motivational activation induced by salient stimuli, and supports the hypothesis that orexin signaling is an important potential therapeutic target for numerous behavioral disorders.

Genome-wide association analysis of composite sleep health scores in 413,904 individuals

Recent genome-wide association studies (GWASs) of several individual sleep traits have identified hundreds of genetic loci, suggesting diverse mechanisms. Moreover, sleep traits are moderately correlated, so together may provide a more complete picture of sleep health, while illuminating distinct domains. Here we construct novel sleep health scores (SHSs) incorporating five core self-report measures: sleep duration, insomnia symptoms, chronotype, snoring, and daytime sleepiness, using additive (SHS-ADD) and five principal components-based (SHS-PCs) approaches. GWASs of these six SHSs identify 28 significant novel loci adjusting for multiple testing on six traits (p < 8.3e-9), along with 341 previously reported loci (p < 5e-08). The heritability of the first three SHS-PCs equals or exceeds that of SHS-ADD (SNP-h2 = 0.094), while revealing sleep-domain-specific genetic discoveries. Significant loci enrich in multiple brain tissues and in metabolic and neuronal pathways. Post-GWAS analyses uncover novel genetic mechanisms underlying sleep health and reveal connections (including potential causal links) to behavioral, psychological, and cardiometabolic traits.

Tissue-specific modulation of NADH consumption as an anti-aging intervention in Drosophila

Aging is characterized by extensive metabolic dysregulation. Redox coenzyme nicotinamide adenine dinucleotide (NAD) can exist in oxidized (NAD+) or reduced (NADH) states, which together form a key NADH/NAD+ redox pair. Total levels of NAD decline with age in a tissue-specific manner, thereby playing a significant role in the aging process. Supplementation with NAD precursors boosts total cellular NAD levels and provides some therapeutic benefits in human clinical trials. However, supplementation studies cannot determine tissue-specific effects of an altered NADH/NAD+ ratio. Here, we created transgenic Drosophila expressing a genetically encoded xenotopic tool LbNOX to directly manipulate the cellular NADH/NAD+ ratio. We found that LbNOX expression in Drosophila impacts both NAD(H) and NADP(H) metabolites in a sex-specific manner. LbNOX rescues neuronal cell death induced by the expression of mutated alpha-B crystallin in the Drosophila eye, a widely used system to study reductive stress. Utilizing LbNOX, we demonstrate that targeting redox NAD metabolism in different tissues may have drastically different outcomes, as the expression of LbNOX solely in the muscle is much more effective for rescuing paraquat-induced oxidative stress compared to whole-body expression. Excitingly, we demonstrate that perturbing NAD(P) metabolism in non-neuronal tissues is sufficient to rejuvenate sleep profiles in aged flies to a youthful state. In summary, we used xenotopic tool LbNOX to identify tissues and metabolic processes which benefited the most from the modulation of the NAD metabolism thereby highlighting important aspects of rebalancing the NAD and NADP pools, all of which can be translated into novel designs of NAD-related human clinical trials.

Unraveling the causal role of sleep traits in development of diabetic retinopathy: A UK Biobank observational study and Mendelian randomization

AIMS

To evaluate the potential causal role of sleep traits (STs) on diabetic retinopathy (DR).

METHODS

The cross-sectional study included 23,851 patients with type 2 diabetes from the UK Biobank and used multivariate logistic models to investigate the observational association between STs and DR. Genetic correlation analysis and two-sample Mendelian randomization (MR) were conducted using ST data from the UK Biobank and DR data from the FinnGen consortium to investigate the genetic and causal associations between STs and DR.

RESULTS

Patients who experienced daytime sleepiness often/all of the time had a higher risk for DR (OR: 1.40; 95% CI, 1.09-1.79; p = .008) compared with those who sometimes/never/rarely experienced daytime sleepiness. Genetic correlations between several STs and DR were detected by cross-trait linkage disequilibrium score regression. MR suggested a causal effect of self-reported daytime sleepiness (OR: 4.08; 95% CI, 1.44-11.61; p = .008), and accelerator-derived sleep duration (OR: 0.73; 95% CI, 0.54-0.98; p = .036) and sleep efficiency (OR: 0.54; 95% CI, 0.36-0.80; p = .002) on DR.

CONCLUSIONS

STs may have a potential causal role for DR. Attention should be paid to the STs of patients for better prevention and treatment of DR.

Relationships between orofacial pain and sleep: Analysis of UK biobank and genome-wide association studies data

Background/purpose

Orofacial pain is common in dental practices. This study aimed to explore relationships between orofacial pain and sleep using the UK Biobank dataset and, based on epidemiological associations, to investigate the causal association using genome-wide association studies data.

Materials and methods

First, a cross-sectional study was conducted with 196,490 participants from UK Biobank. Information on pain conditions and sleep traits was collected. Multivariable models were used to explore the relationships with odds ratio (OR). Second, Mendelian randomization analyses were conducted using data for orofacial pain, including temporomandibular joint disorders-related pain (n = 377,277) and atypical facial pain (n = 331,749), and sleep traits, including sleep duration (n = 446,118), short sleep (n = 411,934), long sleep (n = 339,926), snoring (n = 359,916), ease of getting up (n = 385,949), insomnia (n = 453,379), daytime dozing (n = 452,071), daytime napping (n = 452,633), and chronotype (n = 403,195).

Results

The cross-sectional study confirmed the bidirectionality between pain and sleep. Participants experiencing pain all over the body showed a significant association with an unhealthy sleep pattern (OR = 1.18, P < 0.001) and other sleep traits (P < 0.05). Risks of chronic orofacial pain were associated with sleep duration in a non-linear relationship (P = 0.032). The Mendelian randomization analyses indicated that long sleep was causally associated with temporomandibular joint disorders-related pain (OR = 6.77, P = 0.006).

Conclusion

The relationship between pain and sleep is bidirectional. Long sleep is found to be causally associated with chronic orofacial pain.

Clinical and genetic associations for night eating syndrome in a patient biobank

OBJECTIVE

Night eating syndrome (NES) is an eating disorder characterized by evening hyperphagia. Despite having a prevalence comparable to some other eating disorders, NES remains sparsely investigated and poorly characterized. The present study examined the phenotypic and genetic associations for NES in the clinical Mass General Brigham Biobank.

METHOD

Cases of NES were identified through relevant billing codes for eating disorders (F50.89/F50.9) and subsequent chart review; patients likely without NES were set as controls. Other diagnoses were determined from billing codes and collapsed into one of 1,857 distinct phenotypes based on clinical similarity. NES associations with diagnoses were systematically conducted in phenome-wide association scans using logistic regression models with adjustments for age, sex, race, and ethnicity. Polygenic scores for six related traits, namely for anorexia nervosa, depression, insomnia, sleep apnea, obesity, and type 2 diabetes were tested for associations with NES among participants of European ancestry using adjusted logistic regression models.

RESULTS

Phenome-wide scans comparing patients with NES against controls (cases n = 88; controls n = 64,539) identified associations with 159 clinical diagnoses spanning 13 broad disease groups including endocrine/metabolic and digestive diseases. Notable associations were evident for bariatric surgery, vitamin D deficiency, sleep disorders (sleep apnea, insomnia, and restless legs syndrome), and attention deficit hyperactivity disorder. The polygenic scores for insomnia and obesity were associated with higher odds of NES (insomnia: odds ratio [OR], 1.24; 95% CI, 1.07, 1.43; obesity: 1.98; 95% CI, 1.71, 2.28).

DISCUSSION

Complementary phenome-wide and genetic exploratory analyses provided information on unique and shared features of NES, offering insights that may facilitate its precise definition, diagnosis, and the development of targeted therapeutic interventions.

Causal Associations Between Sleep Traits and Delirium: A Bidirectional Two-Sample Mendelian Randomization Study

Purpose

Numerous studies have identified a correlation between sleep and delirium; however, the causal relationship remains ambiguous. This bidirectional two-sample Mendelian randomization (MR) study was conducted to examine the possible causal relationships between sleep traits and delirium.

Patients and Methods

Utilizing genome-wide association studies (GWAS), we identified ten sleep traits: chronotype, sleep duration, short sleep duration, long sleep duration, daytime napping, daytime sleepiness, insomnia, number of sleep episodes (NSE), sleep efficiency, and rapid eye movement sleep behavior disorder (RBD). In this MR study, genetic variants independently associated with exposures were selected as instrumental variables (IVs). To establish causal inferences, three regression models were employed-inverse variance weighted (IVW), MR Egger, and weighted median (WM) -and conducted sensitivity analyses to assess the robustness of our findings.

Results

Our results suggest no significant causal association between the ten sleep traits and the risk of delirium. The reverse MR analysis revealed that delirium is associated with an increased propensity for morning chronotype [ORIVW, 1.025; 95% CI, 1.012-1.036; p = 1.50E-05; adjusted p values (padjusted)= 1.35E-04] and a decreased risk of long sleep duration [ORIVW, 0.996; 95% CI, 0.993-0.999; p = 0.013; padjusted= 0.059]. However, no robust evidence currently exists to substantiate a causal relationship between delirium and other sleep traits.

Conclusion

Our bidirectional, two-sample MR analysis study did not provide definitive evidence that sleep traits may augment the susceptibility to delirium. However, the reverse MR results indicate that delirium may predispose patients to an earlier sleep-wake cycle. Additional large-scale investigations are necessary to examine the bidirectional causality between delirium and sleep traits.

A conserved role for ALG10/ALG10B and the N -glycosylation pathway in the sleep-epilepsy axis

Congenital disorders of glycosylation (CDG) comprise a class of inborn errors of metabolism resulting from pathogenic variants in genes coding for enzymes involved in the asparagine-linked glycosylation of proteins. Unexpectedly to date, no CDG has been described for ALG10 , encoding the alpha-1,2-glucosyltransferase catalyzing the final step of lipid-linked oligosaccharide biosynthesis. Genome-wide association studies (GWAS) of human traits in the UK Biobank revealed significant SNP associations with short sleep duration, reduced napping frequency, later sleep timing and evening diurnal preference as well as cardiac traits at a genomic locus containing a pair of paralogous enzymes ALG10 and ALG10B . Modeling Alg10 loss in Drosophila, we identify an essential role for the N -glycosylation pathway in maintaining appropriate neuronal firing activity, healthy sleep, preventing seizures, and cardiovascular homeostasis. We further confirm the broader relevance of neurological findings associated with Alg10 from humans and flies using zebrafish and nematodes and demonstrate conserved biochemical roles for N -glycosylation in Arabidopsis . We report a human subject homozygous for variants in both ALG10 and ALG10B arising from a consanguineous marriage, with epilepsy, brain atrophy, and sleep abnormalities as predicted by the fly phenotype. Quantitative glycoproteomic analysis in our Drosophila model identifies potential key molecular targets for neurological symptoms of CDGs.

Improvement in self-reported, but not actigraphic, sleep measures with suvorexant in people with well-controlled Restless Legs Syndrome and persistent insomnia

BACKGROUND

Sleep disturbance remains common in people with Restless Legs Syndrome (RLS), even after RLS symptoms are sufficiently controlled with medication. We conducted a placebo-controlled crossover trial to examine the efficacy of suvorexant in improving sleep quality and quantity in people with well-controlled RLS and persistent insomnia.

METHODS

In this double-blind, randomized, placebo-controlled crossover trial, 34 participants (70.6 % female, mean age = 62.7) with well-controlled RLS were randomized to placebo or suvorexant (10-20 mg) for 6 weeks, followed by a 2-week washout and then the opposite treatment. Study inclusion required an IRLS score <15, insomnia diagnosis per DSM-5, and a diary-reported combined Sleep Onset Latency (SOL) and Wake After Sleep Onset (WASO) > 45 min and a Total Sleep Time (TST) < 7 h on 7/14 baseline nights. The primary outcome was actigraphically-derived TST, and secondary outcomes were Insomnia Severity Index (ISI) score and actigraphically-derived WASO. Data for all sleep metrics were collected at baseline and for the last two weeks of each treatment period.

RESULTS

There were no significant improvements in actigraphically-derived TST (p = 0.58) or WASO (p = 0.99) while taking suvorexant compared to placebo. However, there were significant reductions in insomnia symptoms, measured by the ISI, as well as increases in diary-reported TST (p = 0.01) while taking suvorexant compared to placebo. The most commonly reported side effect of suvorexant was fatigue (29.4 %).

CONCLUSIONS

We observed no significant differences between treatments in actigraphically-derived sleep measures, but support for suvorexant's benefit for overall insomnia and self-reported quantity of sleep in people with well-controlled RLS who continue to suffer from insomnia.

CLINICAL TRIALS REGISTRATION NUMBER

NCT04706091.

Associations between insomnia and cardiovascular diseases: a meta-review and meta-analysis of observational and Mendelian randomization studies

STUDY OBJECTIVES

Observational studies suggest associations between insomnia and cardiovascular diseases (CVDs), but the causal mechanism remains unclear. We investigated the potential causal associations between insomnia and CVDs by a combined systematic meta-review and meta-analysis of observational and Mendelian randomization studies.

METHODS

We searched PubMed, Web of Science, and Embase for English-language articles from inception to July 11, 2023. Two reviewers independently screened the articles to minimize potential bias. We summarized the current evidence on the associations of insomnia with coronary artery disease, atrial fibrillation, heart failure, myocardial infarction, hypertension, and stroke risk by combining meta-analyses of observational and Mendelian randomization studies.

RESULTS

Four meta-analyses of observational studies and 9 Mendelian randomization studies were included in the final data analysis. A systematic meta-review of observational studies provided strong evidence that insomnia is an independent risk factor for many CVDs, including atrial fibrillation, myocardial infarction, and hypertension. A meta-analysis of Mendelian randomization studies revealed that insomnia may be potentially causally related to coronary artery disease (odds ratio [OR] = 1.14, 95% confidence interval [CI] = 1.10-1.19, I2 = 97%), atrial fibrillation (OR = 1.02, 95% CI = 1.01-1.04, I2 = 94%), heart failure (OR = 1.04, 95% CI = 1.03-1.06, I2 =97%), hypertension (OR = 1.16, 95% CI = 1.13-1.18, I2 = 28%), large artery stroke (OR = 1.14, 95% CI = 1.05-1.24, I2 = 0%), any ischemic stroke (OR = 1.09, 95% CI = 1.03-1.14, I2 = 60%), and primary intracranial hemorrhage (OR = 1.16, 95% CI = 1.05-1.27, I2 = 0%). No evidence suggested that insomnia is causally associated with cardioembolic or small vessel stroke.

CONCLUSIONS

Our results provide strong evidence supporting a possible causal association between insomnia and CVD risk. Strategies to treat insomnia may be promising targets for preventing CVDs.

CITATION

Zhang X, Sun Y, Ye S, et al. Associations between insomnia and cardiovascular diseases: a meta-review and meta-analysis of observational and Mendelian randomization studies. J Clin Sleep Med. 2024;20(12):1975-1984.

Sleep risk factors modify the association between c-reactive protein and type 2 diabetes: A prospective cohort study

OBJECTIVE

To investigate the prospective association between serum CRP levels and T2D incidence and explore whether such association was modified by sleep risk factors.

METHODS

The study included 366 746 participants without diabetes and exhibited CRP measures at baseline from the UK Biobank. Sleep risk factors included sleep duration, insomnia, snoring, chronotype, and daytime sleepiness. Cox proportional hazards model was used to estimate the hazard ratio (HR), and 95 % confidence interval (CI) of T2D associated with CRP levels. Interactions between CRP and sleep risk factors were also tested.

RESULTS

During a median follow-up of 10.4 years, 14 200 T2D cases were identified. The HRs (95 % CIs) of T2D were 1.31 (1.21-1.43), 1.62 (1.50-1.75), 1.98 (1.83-2.13), and 2.38 (2.21-2.57), respectively, in higher quintile groups of CRP levels compared with the lowest group (p-value for trend <0.001). There were interactions of CRP levels with self-reported sleep duration, snoring, and daytime sleepiness (p-value for interaction = 0.002, 0.0002, and 0.0001). The associated risks between T2D and the elevation in CRP were more evident among participants with high-risk sleep factors.

CONCLUSIONS

Our study indicates that the elevation in serum CRP levels is associated with a higher T2D incidence; and such relation is modified by sleep risk factors including sleep duration, snoring, and daytime sleepiness.

Clinical associations with treatment resistance in depression: An electronic health record study

Treatment resistance is common in major depressive disorder (MDD), yet clinical risk factors are not well understood. Using a discovery-replication design, we conducted phenome-wide association studies (PheWASs) of MDD treatment resistance in two electronic health record (EHR)-linked biobanks. The PheWAS included participants with an MDD diagnosis in the EHR and at least one antidepressant (AD) prescription. Participant lifetime diagnoses were mapped to phecodes. PheWASs were conducted for three treatment resistance outcomes based on AD prescription data: number of unique ADs prescribed, ≥1 and ≥2 CE switches. Of the 180 phecodes significantly associated with these outcomes in the discovery cohort (n = 12,558), 71 replicated (n = 8,206). In addition to identifying known clinical factors for treatment resistance in MDD, the total unique AD prescriptions was associated with additional clinical variables including irritable bowel syndrome, gastroesophageal reflux disease, symptomatic menopause, and spondylosis. We calculated polygenic risk of specific-associated conditions and tested their association with AD outcomes revealing that genetic risk for many of these conditions is also associated with the total unique AD prescriptions. The number of unique ADs prescribed, which is easily assessed in EHRs, provides a more nuanced measure of treatment resistance, and may facilitate future research and clinical application in this area.

Unraveling the heart-brain axis: shared genetic mechanisms in cardiovascular diseases and Schizophrenia

The comorbidity between cardiovascular diseases (CVD) and schizophrenia (SCZ) has attracted widespread attention from researchers, with shared genetic causes potentially providing important insights into their association. This study conducted a comprehensive analysis of genetic data from 17 types of CVD and SCZ using genome-wide multi-trait association studies (GWAS), employing statistical methods such as LDSC, MTAG, LAVA, and bidirectional Mendelian randomization to explore global and local genetic correlations and identify pleiotropic single nucleotide variants (SNVs). The analysis revealed a significant genetic correlation between CVD and SCZ, identifying 842 potential pleiotropic single nucleotide variants (SNVs) and multiple associated biological pathways. Notably, genes such as TRIM27, CENPM, and MYH7B played critical roles in the shared genetic variations of both types of diseases. This study reveals the complex genetic relationship between CVD and SCZ, highlighting potential shared biological mechanisms involving immune responses, metabolic factors, and neurodevelopmental processes, thereby providing new directions for future interventions and treatments.

Navigating Mendelian Randomization in Sleep Medicine: Challenges, Opportunities, and Best Practices

Mendelian randomization (MR) has become an influential method for elucidating causal links between sleep traits and disorders, and health outcomes. This article provides sleep medicine specialists with an overview of MR, emphasizing its applications and limitations in health research, particularly in the context of sleep research. The article addresses key challenges in conducting and interpreting MR studies on sleep, focusing on the core assumptions of relevance, exchangeability, and exclusion restriction. The importance of proper genetic instrument selection, bias mitigation, and cautious result interpretation is emphasized. Strategies are recommended to enhance the quality of MR studies in sleep medicine, including collaborations between MR experts and sleep specialists. The paper also explores sleep medicine-specific issues like analyzing binary traits and addressing heterogeneity in pooled analyses. Guidance is provided on transparent reporting of MR findings, stressing the need for comprehensive effect estimates, confidence intervals, and p-values. We conclude by advocating for rigorous MR implementation in sleep research to deepen our understanding of sleep-health relationships. By following best practices in study design, analysis, and reporting, researchers can reinforce the credibility and impact of MR findings in sleep medicine, ultimately improving patient care and public health strategies.

Causal impacts of smoking on pain conditions and the mediating pathways: a mendelian randomization study

Smoking is a risk factor for multiple diseases. We performed mendelian randomization (MR) analyses to investigate the causal association of smoking initiation on pain conditions and the potential mediating pathways. Genetic associated with smoking initiation at the genome-wide significance level were selected as instrumental variables. Genetic associations with 10 pain conditions were derived from the FinnGen and UK Biobank study. Multivariable MR analysis was conducted to explore the mediation effects of depression, insomnia and sedentary behavior. A series of sensitivity analyses were conducted to assess the stability of our research findings. Genetic liability to smoking initiation was associated with an increased risk of angina pectoris, dorsalgia, low back pain, pain in limb, pain in joint, pain in thoracic spine and sciatica in both FinnGen and UK Biobank study. These causal associations were largely mediated by major depression (2.9- 39.5%), sedentary behavior (13.0- 31.2%), insomnia (10.3- 33.1%) and combination of all three mediators (30.2- 65.3%). The effects of smoking on outcomes were partly attenuated after adjusting for depression, sedentary behavior and insomnia respectively, and the direct effect of smoking initiation on pain was diminished toward null after adjusting for combined three mediators. These results were robust to sensitivity analyses. Our findings illustrated the causal effect of smoking and a broad range of pain conditions, and major depression, sedentary behavior and insomnia mediate many of these associations.

Interactions Between Eleven Sleep-Related Characteristics and Diabetic Nephropathy: A Bidirectional Mendelian Randomization Study in European Population

OBJECTIVE

Observational studies often report disturbed sleep patterns in individuals with diabetic nephropathy (DN). The possible causal relationship behind these connections remains unknown. This research assessed the possible cause-and-effect relationship between eleven sleep-related characteristics and the risk of developing DN using a two-sample Mendelian randomization (MR) study.

METHODS

This study employed a two-sample bidirectional MR analytical approach. Genetic data for eleven sleep-related characteristics were acquired from the genome-wide association studies (GWAS) database of individuals of European ancestry which involve scanning complete sets of DNA, or genomes. GWAS summary data for DN included 4,111 DN cases and 308,539 controls. Instrumental variables were single nucleotide polymorphisms strongly linked to sleep-related characteristics. The main analysis used the random-effects inverse variance weighted (IVW) approach, with validation through sensitivity testing.

RESULTS

MR analysis revealed that a higher genetic predisposition for sleep efficiency reduced the chance of developing DN (odds ratio [OR]: 0.384; 95% confidence interval [CI] 0.205-0.717; p=0.003). Genetic susceptibility to DN was associated with a higher likelihood of experiencing more sleep episodes (OR: 1.015; 95% CI 1.003-1.028; p=0.016). Sensitivity analysis confirmed the robustness of these correlations. No significant connections were found between other genetically predicted sleep characteristics and the likelihood of developing DN.

CONCLUSION

Our research indicates that a genetic predisposition for better sleep efficiency is linked to a lower risk of developing DN. There is also evidence suggesting that genetic predisposition to DN may directly impact sleep episodes. Further research is needed to explore the molecular mechanisms underlying these findings.

Genetically predicted effects of 10 sleep phenotypes on revision of knee arthroplasty: a mendelian randomization study

BACKGROUND

Accumulating evidence has suggested that sleep disturbances and disorders are common in patients who undergo knee arthroplasty. Revision surgery represents one of the most catastrophic outcomes of knee arthroplasty. However, it remains unclear whether sleep traits are the causes or consequences of knee arthroplasty revision. This study aimed to genetically examine the relationships between sleep traits and knee arthroplasty revision.

METHODS

To determine the causal relationship between sleep traits and knee arthroplasty revision, we employed two-sample Mendelian randomization (MR) using summary statistics from the largest publicly available genome-wide association studies (GWASs). The MR design uses genetic variants as instrumental variables to help separate causal relationships from non-causal associations. The main analyses included an inverse variance weighted (IVW) meta-analysis to obtain primary effect estimates. Sensitivity analyses involving the weighted median approach and MR-Egger regression were also conducted to check for potential pleiotropic biases. Numerous complementary sensitivity analyses were also performed to identify statistically significant causal correlations when there were horizontal pleiotropy and heterogeneity across variants. Finally, a reverse MR analysis was performed to evaluate the possibility of reverse causation.

RESULTS

In the absence of heterogeneity and horizontal pleiotropy, the IVW method revealed that genetically-predicted short sleep duration short sleep duration (average sleep duration of 24 h is 6 h or less) was positively correlated with the risk of knee arthroplasty revision (odds ratio = 1.03, 95% confidence interval = 1.01-1.05, and P = 0.003), while the association between genetically-predicted long sleep duration and knee arthroplasty was negative. The reverse MR analysis did not yield evidence supporting reverse causality relation between knee arthroplasty revision and sleep phenotypes.

CONCLUSION

This research indicated that, of the 10 sleep phenotypes we analyzed, only sleep duration was causally associated with knee arthroplasty revision. These discoveries added to the understanding of the role of sleep traits in the etiology of knee arthroplasty revision, which might further expand our insights into the prevention of knee arthroplasty revision.

Sleep inertia drives the association of evening chronotype with psychiatric disorders: epidemiological and genetic evidence

Evening chronotypes (a.k.a. "night-owls") are held to be at greater risk for psychiatric disorders. This is postulated to be due to delayed circadian timing increasing the likelihood of circadian misalignment in an early-oriented society. Circadian misalignment is known to heighten sleep inertia, the difficulty transitioning from sleep to wake characterized by low arousal and cognitive impairment, and evening chronotypes experience greater sleep inertia. Therefore, difficulty awakening may explain the relationship between evening chronotype and psychiatric disorders by acting as a biomarker of circadian misalignment. In analyzing the longitudinal incidence of psychiatric disorders in the UK Biobank (n = 496,820), we found that evening chronotype predicted increased incidence of major depressive disorder, schizophrenia, generalized anxiety disorder and bipolar disorder. Crucially, this effect was dependent on sleep inertia, which was a much stronger predictor of these disorders, such that evening types without sleep inertia were at no higher risk as compared to morning types. Longitudinal analyses of suicide and depressed mood (CES-D score) in the Older Finnish Twin Cohort (n = 23,854) replicated this pattern of results. Twin and genome-wide association analyses of difficulty awakening identified the trait to be heritable (Twin H 2 = 0.40; SNP h 2 = 0.08), enriched for circadian rhythms genes and have substantial shared genetic architecture with chronotype. Marginal and conditional Mendelian randomization analyses mirrored the epidemiological results, such that the causal effect of evening chronotype on psychiatric disorders was driven by shared genetic architecture with difficulty awakening. In contrast, difficult awakening was strongly causally associated with psychiatric disorders independently of chronotype. Psychiatric disorders were only weakly reverse causally linked to difficult awakening. Collectively, these results challenge the notion that evening chronotype is a risk factor for psychiatric disorders per se, suggesting instead that evening types are at greater risk for psychiatric disorders due to circadian misalignment, for which sleep inertia may be acting as a biomarker.

Genetic estimation of causalities between educational attainment with common digestive tract diseases and the mediating pathways

BACKGROUND

The association between education, intelligence, and cognition with digestive tract diseases has been established. However, the specific contribution of each factor in the pathogenesis of these diseases are still uncertain.

METHOD

This study employed multivariable Mendelian randomization (MR) to assess the independent effects of education, intelligence, and cognition on gastrointestinal conditions in the FinnGen and UK Biobank European-ancestry populations. A two-step MR approach was employed to assess the mediating effects of the association.

RESULTS

Meta-analysis of MR estimates from FinnGen and UK Biobank showed that 1- SD (4.2 years) higher education was causally associated with lower risks of gastroesophageal reflux (OR: 0.58; 95% CI: 0.50, 0.66), peptic ulcer (OR: 0.57; 95% CI: 0.47, 0.69), irritable bowel syndrome (OR: 0.70; 95% CI: 0.56, 0.87), diverticular disease (OR: 0.69; 95% CI: 0.61, 0.78), cholelithiasis (OR: 0.68; 95% CI: 0.59, 0.79) and acute pancreatitis (OR: 0.54; 95% CI: 0.41, 0.72), independently of intelligence and cognition. These causal associations were mediating by body mass index (3.7-22.3%), waist-to-hip ratio (8.3-11.9%), body fat percentage (4.1-39.8%), fasting insulin (1.4-5.5%) and major depression (6.0-12.4%).

CONCLUSION

Our findings demonstrate a causal and independent association between education and six common digestive tract diseases. Additionally, our study highlights five mediators as crucial targets for preventing digestive tract diseases associated with lower education levels.

Causal relationships between neuropsychiatric disorders and nonalcoholic fatty liver disease: A bidirectional Mendelian randomization study

BACKGROUND

Increasing evidences suggest that nonalcoholic fatty liver disease (NAFLD) is associated with neuropsychiatric disorders. Nevertheless, whether there were causal associations between them remained vague. A causal association between neuropsychiatric disorders and NAFLD was investigated in this study.

METHODS

We assessed the published genome-wide association study summary statistics for NAFLD, seven mental disorder-related diseases and six central nervous system dysfunction-related diseases. The causal relationships were first assessed using two-sample and multivariable Mendelian randomization (MR). Then, sensitivity analyses were performed, followed by a reverse MR analysis to determine whether reverse causality is possible. Finally, we performed replication analyses and combined the findings from the above studies.

RESULTS

Our meta-analysis results showed NAFLD significantly increased the risk of anxiety disorders (OR = 1.016, 95% CI = 1.010-1.021, P value < 0.0001). In addition, major depressive disorder was the potential risk factor for NAFLD (OR = 1.233, 95% CI = 1.063-1.430, P value = 0.006). Multivariable MR analysis showed that the causal effect of major depressive disorder on NAFLD remained significant after considering body mass index, but the association disappeared after adjusting for the effect of waist circumference. Furthermore, other neuropsychiatric disorders and NAFLD were not found to be causally related.

CONCLUSIONS

These results implied causal relationships of NAFLD with anxiety disorders and Major Depressive Disorder. This study highlighted the need to recognize and understand the connection between neuropsychiatric disorders and NAFLD to prevent the development of related diseases.

Executive Function and Impulsivity Predict Distinct Genetic Variance in Internalizing Problems, Externalizing Problems, Thought Disorders, and Compulsive Disorders: A Genomic Structural Equation Modeling Study

Individual differences in self-control predict many health and life outcomes. Building on twin literature, we used genomic structural equation modeling to test the hypothesis that genetic influences on executive function and impulsivity predict independent variance in mental health and other outcomes. The impulsivity factor (comprising urgency, lack of premeditation, and other facets) was only modestly genetically correlated with low executive function (rg =.13). Controlling for impulsivity, low executive function was genetically associated with increased internalizing (βg =.15), externalizing (βg =.13), thought disorders (βg =.38), compulsive disorders (βg =.22), and chronotype (βg =.11). Controlling for executive function, impulsivity was positively genetically associated with internalizing (βg =.36), externalizing (βg =.55), body mass index (βg =.26), and insomnia (βg =.35), and negatively genetically associated with compulsive disorders (βg = -.17). Executive function and impulsivity were both genetically correlated with general cognitive ability and educational attainment. This work suggests that executive function and impulsivity are genetically separable and show independent associations with mental health.

Estimating the direct effects of the genetic liabilities to bipolar disorder, schizophrenia, and behavioral traits on suicide attempt using a multivariable Mendelian randomization approach

Bipolar disorder (BD) and schizophrenia (SZ) are associated with higher odds of suicide attempt (SA). In this study, we aimed to explore the effect of BD and SZ genetic liabilities on SA, also considering the contribution of behavioral traits, socioeconomic factors, and substance use disorders. Leveraging large-scale genome-wide association data from the Psychiatric Genomics Consortium (PGC) and the UK Biobank (UKB), we conducted a two-sample Mendelian randomization (MR) analysis to evaluate the putative causal effect of BD (41,917 cases, 371,549 controls) and SZ (53,386 cases, 77,258 controls) on SA (26,590 cases, 492,022 controls). Then, we assessed the putative causal effect of BD and SZ on behavioral traits, socioeconomic factors, and substance use disorders. Considering the associations identified, we evaluated the direct causal effect of behavioral traits, socioeconomic factors, and substance use disorders on SA using a multivariable MR approach. The genetic liabilities to BD and SZ were associated with higher odds of SA (BD odds ratio (OR) = 1.24, p = 3.88 × 10-12; SZ OR = 1.09, p = 2.44 × 10-20). However, while the effect of mental distress (OR = 1.17, p = 1.02 × 10-4) and risk-taking (OR = 1.52, p = 0.028) on SA was independent of SZ genetic liability, the BD-SA relationship appeared to account for the effect of these risk factors. Similarly, the association with loneliness on SA was null after accounting for the effect of SZ genetic liability. These findings highlight the complex interplay between genetic risk of psychiatric disorders and behavioral traits in the context of SA, suggesting the need for a comprehensive mental health assessment for high-risk individuals.

No genetic association between sleep traits and periodontitis: A bidirectional two-sample Mendelian randomization study

OBJECTIVE

This study aimed to investigate the potential genetic link between sleep traits and periodontitis.

METHODS

A two-sample bidirectional Mendelian randomization (MR) analysis was conducted using publicly available genome-wide association studies data on chronotype, daytime sleepiness, daytime napping frequency, insomnia, sleep duration, snoring, and the apnea-hypopnea index (AHI), along with a separate dataset on periodontitis.

RESULTS

Chronotype (OR = 0.929, 95% CI = 0.788-1.095), daytime sleepiness (OR = 0.492, 95% CI = 0.186-1.306), daytime napping frequency (OR = 1.178, 95% CI = 0.745-1.863), sleep duration (OR = 0.868, 95% CI = 0.644-1.169), AHI (OR = 1.124, 95% CI = 0.980-1.289), insomnia (OR = 0.832, 95% CI = 0.440-1.573), and snoring (OR = 0.641, 95% CI = 0.198-2.075) had no effect on periodontitis. Similarly, periodontitis demonstrated no significant effect on sleep traits.

CONCLUSIONS

There is no evidence of a bidirectional genetic relationship between sleep traits and the risk of periodontitis.

Perceived Stress, but Not Rumination, Mediates the Relationship Between Trait Mindfulness and Sleep Quality in Young Adults

Objective

Poor sleep among young adults is prevalent, yet the mediating variables are largely understudied, and there is limited relevant work utilizing objective sleep measures. The present study investigated the mediating effects of perceived stress and rumination in the relationship between trait mindfulness and subjective and objective sleep quality in young adults.

Methods

A total of 170 healthy adults (aged 18-37, M = 20.8, SD = 2.9) self-reported on trait mindfulness, perceived stress, and rumination. The primary (N = 140) and secondary (N = 30) samples both completed the Pittsburgh Sleep Quality Index (PSQI) to assess subjective sleep quality. The secondary sample (N = 30) additionally provided sleep diaries, as well as wrist-worn actigraphy data for assessing objective sleep quality. A mediation analysis was conducted to assess the effect of trait mindfulness on sleep quality with perceived stress and rumination as mediators.

Results

Trait mindfulness was positively associated with better subjective sleep quality; this was fully mediated by perceived stress, b = -0.08, 95% CI [-.12, -0.06]. Rumination was negatively associated with subjective sleep quality but did not mediate the relationship between trait mindfulness and sleep quality, b = -0.01, 95% CI [-.03, 0.02]. Only trait mindfulness was correlated with diary-based sleep ratings, and none of the measures were associated with actigraphy-based sleep quality.

Conclusion

This study indicates that perceived stress is an important mediator in the relationship between trait mindfulness and subjective sleep quality among young adults, rather than rumination. These findings have implications for mindfulness-based therapeutic approaches to address the high prevalence of sleep disorders among young adults, adding mechanistic detail to the literature.

The role of hypertension in the relationship between leisure screen time, physical activity and migraine: a 2-sample Mendelian randomization study

BACKGROUND

The relationship between lifestyle and migraine is complex, as it remains uncertain which specific lifestyle factors play the most prominent role in the development of migraine, or which modifiable metabolic traits serve as mediators in establishing causality.

METHODS

Independent genetic variants strongly associated with 20 lifestyle factors were selected as instrumental variables from corresponding genome-wide association studies (GWASs). Summary-level data for migraine were obtained from the FinnGen consortium (18,477 cases and 287,837 controls) as a discovery set and the GWAS meta-analysis data (26,052 cases and 487,214 controls) as a replication set. Estimates derived from the two datasets were combined using fixed-effects meta-analysis. Two-step univariable MR (UVMR) and multivariable Mendelian randomization (MVMR) analyses were conducted to evaluate 19 potential mediators of association and determine the proportions of these mediators.

RESULTS

The combined effect of inverse variance weighted revealed that a one standard deviation (SD) increase in genetically predicted Leisure screen time (LST) was associated with a 27.7% increase (95% CI: 1.14-1.44) in migraine risk, while Moderate or/and vigorous physical activity (MVPA) was associated with a 26.9% decrease (95% CI: 0.61-0.87) in migraine risk. The results of the mediation analysis indicated that out of the 19 modifiable metabolic risk factors examined, hypertension explains 24.81% of the relationship between LST and the risk of experiencing migraine. Furthermore, hypertension and diastolic blood pressure (DBP) partially weaken the association between MVPA and migraines, mediating 4.86% and 4.66% respectively.

CONCLUSION

Our research findings indicated that both LST and MVPA in lifestyle have independent causal effects on migraine. Additionally, we have identified that hypertension and DBP play a mediating role in the causal pathway between these two factors and migraine.

Genetic variants affect diurnal glucose levels throughout the day

Circadian rhythms not only coordinate the timing of wake and sleep but also regulate homeostasis within the body, including glucose metabolism. However, the genetic variants that contribute to temporal control of glucose levels have not been previously examined. Using data from 420,000 individuals from the UK Biobank and replicating our findings in 100,000 individuals from the Estonian Biobank, we show that diurnal serum glucose is under genetic control. We discover a robust temporal association of glucose levels at the Melatonin receptor 1B ( MTNR1B) (rs10830963, P = 1e-22) and a canonical circadian pacemaker gene Cryptochrome 2 ( CRY2) loci (rs12419690, P = 1e-16). Furthermore, we show that sleep modulates serum glucose levels and the genetic variants have a separate mechanism of diurnal control. Finally, we show that these variants independently modulate risk of type 2 diabetes. Our findings, together with earlier genetic and epidemiological evidence, show a clear connection between sleep and metabolism and highlight variation at MTNR1B and CRY2 as temporal regulators for glucose levels.

Genetic correlation and causal relationship between sleep and myopia: a mendelian randomization study

Purpose

To investigate the genetic correlation and causal links between sleep traits (including sleep duration, chronotype, and insomnia) and myopia.

Methods

Summary data on three sleep traits (sleep duration, chronotype and insomnia) and myopia from FinnGen (n = 214,211) and UK Biobank (n = 460,536) were analyzed using linkage disequilibrium score regression (LD Score), univariable and multivariable mendelian randomization (MR) experiments and Causal Analysis Using Summary Effect (CAUSE) estimation.

Results

LD Score regression detected candidate genetic correlation between sleep traits and myopia, such as sleep duration, chronotype (Genetic Correlation Z-score >10.00, h2_observed_p < 0.005, Lambda GC > 1.05, p > 0.05). Univariable MR analyses indicated that increased sleep duration has a promotional effect on the occurrence of myopia (p = 0.046 < 0.05, P_FDR = 0.138 < 0.2, OR = 2.872, 95% CI: 1.018-8.101). However, after accounting for potential confounding factors, multivariable MR and CAUSE analysis did not provide evidence for a causal effect of the three sleep traits on myopia.

Conclusion

There may be a potential genetic correlation between sleep duration, chronotype and myopia. However, neither of sleep duration, chronotype or insomnia had causal effect on myopia.

Dissecting the genetic and causal relationship between sleep-related traits and common brain disorders

BACKGROUND

There is a profound connection between abnormal sleep patterns and brain disorders, suggesting a shared influential association. However, the shared genetic basis and potential causal relationships between sleep-related traits and brain disorders are yet to be fully elucidated.

METHODS

Utilizing linkage disequilibrium score regression (LDSC) and bidirectional two-sample univariable Mendelian Randomization (UVMR) analyses with large-scale GWAS datasets, we investigated the genetic correlations and causal associations across six sleep traits and 24 prevalent brain disorders. Additionally, a multivariable Mendelian Randomization (MVMR) analysis evaluated the cumulative effects of various sleep traits on each brain disorder, complemented by genetic loci characterization to pinpoint pertinent genes and pathways.

RESULTS

LDSC analysis identified significant genetic correlations in 66 out of 144 (45.8 %) pairs between sleep-related traits and brain disorders, with the most pronounced correlations observed in psychiatric disorders (66 %, 48/72). UVMR analysis identified 29 causal relationships (FDR<0.05) between sleep traits and brain disorders, with 19 associations newly discovered according to our knowledge. Notably, major depression, attention-deficit/hyperactivity disorder, bipolar disorder, cannabis use disorder, and anorexia nervosa showed bidirectional causal relations with sleep traits, especially insomnia's marked influence on major depression (IVW beta 0.468, FDR = 5.24E-09). MVMR analysis revealed a nuanced interplay among various sleep traits and their impact on brain disorders. Genetic loci characterization underscored potential genes, such as HOXB2, while further enrichment analyses illuminated the importance of synaptic processes in these relationships.

CONCLUSIONS

This study provides compelling evidence for the causal relationships and shared genetic backgrounds between common sleep-related traits and brain disorders.

Shared genetic mechanisms underlying association between sleep disturbances and depressive symptoms

OBJECTIVES

Polygenic scores (PGS) for sleep disturbances and depressive symptoms in an epidemiological cohort were contrasted. The overlap between genes assigned to variants that compose the PGS predictions was tested to explore the shared genetic bases of sleep problems and depressive symptoms.

METHODS

PGS analysis was performed on the São Paulo Epidemiologic Sleep Study (EPISONO, N = 1042), an adult epidemiological sample. A genome wide association study (GWAS) for depression grounded the PGS calculations for Beck Depression Index (BDI), while insomnia GWAS based the PGS for Insomnia Severity Index (ISI) and Pittsburg Sleep Quality Index (PSQI). Pearson's correlation was applied to contrast PGS and clinical scores. Fisher's Exact and Benjamin-Hochberg tests were used to verify the overlaps between PGS-associated genes and the pathways enriched among their intersections.

RESULTS

All PGS models were significant when individuals were divided as cases or controls according to BDI (R2 = 1.2%, p = 0.00026), PSQI (R2 = 3.3%, p = 0.007) and ISI (R2 = 3.4%, p = 0.021) scales. When clinical scales were used as continuous variables, the PGS models for BDI (R2 = 1.5%, p = 0.0004) and PSQI scores (R2 = 3.3%, p = 0.0057) reached statistical significance. PSQI and BDI scores were correlated, and the same observation was applied to their PGS. Genes assigned to variants that compose the best-fit PGS predictions for sleep quality and depressive symptoms were significantly overlapped. Pathways enriched among the intersect genes are related to synapse function.

CONCLUSIONS

The genetic bases of sleep quality and depressive symptoms are correlated; their implicated genes are significantly overlapped and converge on neural pathways. This data suggests that sleep complaints accompanying depressive symptoms are not secondary issues, but part of the core mental illness.

The role of accelerometer-derived sleep traits on glycated haemoglobin and glucose levels: a Mendelian randomization study

Self-reported shorter/longer sleep duration, insomnia, and evening preference are associated with hyperglycaemia in observational analyses, with similar observations in small studies using accelerometer-derived sleep traits. Mendelian randomization (MR) studies support an effect of self-reported insomnia, but not others, on glycated haemoglobin (HbA1c). To explore potential effects, we used MR methods to assess effects of accelerometer-derived sleep traits (duration, mid-point least active 5-h, mid-point most active 10-h, sleep fragmentation, and efficiency) on HbA1c/glucose in European adults from the UK Biobank (UKB) (n = 73,797) and the MAGIC consortium (n = 146,806). Cross-trait linkage disequilibrium score regression was applied to determine genetic correlations across accelerometer-derived, self-reported sleep traits, and HbA1c/glucose. We found no causal effect of any accelerometer-derived sleep trait on HbA1c or glucose. Similar MR results for self-reported sleep traits in the UKB sub-sample with accelerometer-derived measures suggested our results were not explained by selection bias. Phenotypic and genetic correlation analyses suggested complex relationships between self-reported and accelerometer-derived traits indicating that they may reflect different types of exposure. These findings suggested accelerometer-derived sleep traits do not affect HbA1c. Accelerometer-derived measures of sleep duration and quality might not simply be 'objective' measures of self-reported sleep duration and insomnia, but rather captured different sleep characteristics.