Prospective study of chronotype and incident depression among middle- and older-aged women in the Nurses' Health Study II

Greenspace and depression incidence in the US-based nationwide Nurses' Health Study II: A deep learning analysis of street-view imagery

BACKGROUND

Greenspace exposure is associated with lower depression risk. However, most studies have measured greenspace exposure using satellite-based vegetation indices, leading to potential exposure misclassification and limited policy relevance. We examined the association of street-view greenspace measures with incident depression in a prospective cohort of US women.

METHODS

We applied deep learning segmentation models to 350 million US street-view images nationwide (2007-2020) to derive ground-level greenspace metrics, including percentage of trees, grass, and other greenspace (plants/flowers/fields), and linked metrics to Nurses' Health Study II participants' residences (N = 33,490) within 500 m each year. Cox proportional hazards models estimated the relationship between street-view greenspace metrics and incident depression, assessed through self-report of clinician-diagnosed depression or regular antidepressant use and adjusted for individual- and area-level factors.

FINDINGS

In adjusted models, higher percentages of street-view trees were inversely associated with incident depression (HR per IQR, 0.98; 95%CI: 0.94-1.01) and specifically clinician-diagnosed depression (HR per IQR, 0.94; 95%CI: 0.90-0.99). Higher percentages of street-view grass were also inversely associated with incident depression, but only in areas with low particulate matter (PM2.5) levels (HR per IQR, 0.79; 95%CI: 0.71-0.86). Results were consistent after adjusting for additional spatial and behavioral factors, and persisted after adjusting for traditional satellite-based vegetation indices.

CONCLUSION AND RELEVANCE

We observed participants who lived in areas with more trees visible in street-view images had a lower risk of depression. Our findings suggest tree-planting interventions may reduce depression risk.

Chronotype, sleep quality, depression and pre-sleep rumination: A diary and actigraphy study

Eveningness has been associated with both disturbed sleep and depression. It is unclear, however, if deprived sleep explains evening types' vulnerability to depression. The role of pre-sleep rumination in these associations also remains understudied. The present study assessed the relationship between eveningness and sleep quality, as well as the possible mediating effect of pre-sleep rumination and the moderating effect of a history of depression, under naturalistic conditions. Eighty-eight Dutch-speaking participants (87.5% females, 21.4 ± 3.7 years) were selected on the basis of their non-intermediate chronotype using the Morningness Eveningness Questionnaire (evening types (n = 53); morning types (n = 35)). Depression status was assessed through a diagnostic interview (healthy (n = 61); remitted depressed (n = 27)). Participants' sleep characteristics were monitored via actigraphy and sleep diaries for seven consecutive days and nights. Pre-sleep rumination was measured via a self-report questionnaire. Evening types had longer subjective and actigraphic sleep onset latency than morning types. Pre-sleep rumination did not mediate the former associations but predicted longer subjective sleep onset latency. Furthermore, the relationship between chronotype and subjective sleep onset latency was moderated by depression history. Remitted depressed evening types reported longer sleep onset latency than healthy evening and morning types, possibly posing the former at a higher risk for depressive relapse. Overall, the current findings address the need to further investigate the physiological signature of circadian rhythms and sleep latency. This could serve as a foundation for the development of prevention and early intervention programs, tailored for mood and sleep disorders.

Nonlinear and symptom specific associations between chronotype and depression

The chronotype of individuals has been found to be predictive of depression risk and associated with the severity of depression. However, since depression is a phenotypically heterogeneous disease, it seems improbable that chronotype plays a role in every instance of depression. This study investigates the association between the two, while considering possible symptom-specificity and non-linearity of the relationship, utilizing a large sample from the National Health and Nutrition Examination Survey (N = 5217; 54% female; Age: M = 52.65, SD = 18.76). Depression symptoms were assessed using the Patient Health Questionnaire-9 (PHQ-9), and chronotype was determined by calculating sleep midpoints. Further, we also explored the potential mediating role of systemic inflammation, measured by C-reactive protein (CRP) levels, in the chronotype-depression link. The findings substantiate previous research indicating late chronotypes to be associated with higher PHQ-9 sum scores, with a minimum in PHQ-9 at a sleep midpoint of 02:49. The study further differentiates between individual depression symptoms, uncovering varying patterns of association with chronotype. No significant effect of chronotype on levels of CRP was found, suggesting that the link between chronotype and depression symptoms may not be directly mediated and appears to be stable and independent from systemic inflammation. The study highlights the non-linear and symptom-specific nature of the chronotype-depression connection and suggests the need for further, longitudinal studies to elucidate causal mechanisms and potential mediators.

Evening Chronotypes With Depression Report Poorer Outcomes of Selective Serotonin Reuptake Inhibitors: A Survey-Based Study of Self-Ratings

BACKGROUND

Preliminary evidence suggests that evening chronotype is related to poorer efficacy of selective serotonin reuptake inhibitors. It is unknown whether this is specific to particular medications, self-rated chronotype, or efficacy.

METHODS

In the Australian Genetics of Depression Study (n = 15,108; 75% women; 18-90 years; 68% with ≥1 other lifetime diagnosis), a survey recorded experiences with 10 antidepressants, and the reduced Morningness-Eveningness Questionnaire was used to estimate chronotype. A chronotype polygenic score was calculated. Age- and sex-adjusted regression models (Bonferroni-corrected) estimated associations among antidepressant variables (how well the antidepressant worked [efficacy], duration of symptom improvement, side effects, discontinuation due to side effects) and self-rated and genetic chronotypes.

RESULTS

The chronotype polygenic score explained 4% of the variance in self-rated chronotype (r = 0.21). Higher self-rated eveningness was associated with poorer efficacy of escitalopram (odds ratio [OR] = 1.04; 95% CI, 1.02 to 1.06; p = .000035), citalopram (OR = 1.03; 95% CI, 1.01 to 1.05; p = .004), fluoxetine (OR = 1.03; 95% CI, 1.01 to 1.05; p = .001), sertraline (OR = 1.02; 95% CI, 1.01 to 1.04; p = .0008), and desvenlafaxine (OR = 1.03; 95% CI, 1.01 to 1.05; p = .004), and a profile of increased side effects (80% of those recorded; ORs = 0.93-0.98), with difficulty getting to sleep the most common. Self-rated chronotype was unrelated to duration of improvement or discontinuation. The chronotype polygenic score was only associated with suicidal thoughts and attempted suicide (self-reported). While our measures are imperfect, and not of circadian phase under controlled conditions, the model coefficients suggest that dysregulation of the phenotypic chronotype relative to its genetic proxy drove relationships with antidepressant outcomes.

CONCLUSIONS

The idea that variation in circadian factors influences response to antidepressants was supported and encourages exploration of circadian mechanisms of depressive disorders and antidepressant treatments.

The association of self-reported sleep and circadian measures with glycemic control and diabetes complications among young adults with type 2 diabetes

We aim to examine the association of sleep duration, sleep quality, late chronotype, and circadian misalignment with glycemic control and risk of complications in young adults with youth-onset type 2 diabetes followed in the Treatment Options for Type 2 Diabetes in Adolescents and Youth (TODAY) study. Self-reported sleep duration, quality, timing, and circadian misalignment were assessed via a modified Pittsburgh Sleep Quality Index (PSQI) questionnaire, and chronotype was assessed via the Morningness-Eveningness Questionnaire (MEQ). We examined diabetes complications including loss of glycemic control (defined as hemoglobin A1c ≥8%), hypertension, dyslipidemia, albuminuria, and diabetic peripheral neuropathy. Multivariable logistic regression models were constructed to assess associations between sleep and circadian measures with outcomes of interest, such as loss of glycemic control and diabetes complications. A total of 421 participants (34.2% male), mean age 23.6 ± 2.5 yr, mean body mass index (BMI) of 36.1 ± 8.3 kg/m2, and mean diabetes duration of 10.0 ± 1.5 yr were evaluated. Self-reported short sleep duration, daytime sleepiness, and sleep quality were not associated with loss of glycemic control or diabetes complications. Late self-reported bedtime (after midnight) on work/school nights, rather than self-expressed chronotype or circadian misalignment, was independently associated with loss of glycemic control. An association was seen between late bedtimes and albuminuria but was attenuated after adjusting for depression. In conclusion, late bedtime on work/school days, rather than short sleep duration, daytime sleepiness, or poor sleep quality, was independently associated with loss of glycemic control in this longitudinal cohort of young adults with youth-onset type 2 diabetes.NEW & NOTEWORTHY The prevalence of type 2 diabetes in youth is increasing at an alarming rate. Identifying potentially modifiable factors modulating glycemic control is critically important to reduce micro and macrovascular complications. In a large cohort of youth-onset type 2 diabetes, self-reported late bedtime on work/school days was independently associated with loss of glycemic control in this longitudinal cohort of young adults with youth-onset type 2 diabetes.

Timing and duration of dog walking and dog owner's chronotype in relation to incident depression risk among middle to older-aged female nurses

BACKGROUND

We examined associations between dog ownership, morning dog walking and its timing and duration, and depression risk in female nurses, exploring effect modification by chronotype. We hypothesized that dog ownership and morning walking with the dog are associated with lower odds of depression, and that the latter is particularly beneficial for evening chronotypes by helping them to synchronize their biological clock with the solar system.

METHODS

26,169 depression-free US women aged 53-72 from the Nurses' Health Study 2 (NHS2) were prospectively followed from 2017-2019. We used age- and multivariable-adjusted logistic regression models to estimate odds ratios (ORs) and 95% confidence intervals (95%CIs) for depression according to dog ownership, and morning dog walking, duration, and timing.

RESULTS

Overall, there was no association between owning a dog (ORvs_no_pets = 1.12, 95%CI = 0.91-1.37), morning dog walking (ORvs_not = 0.87, 95%CI = 0.64-1.18), or the duration (OR>30min vs. ≤15mins = 0.68, 95%CI = 0.35-1.29) or timing of morning dog walks (ORafter9am vs. before7am = 1.06, 95%CI = 0.54-2.05) and depression. Chronotype of dog owners appeared to modify these associations. Compared to women of the same chronotype but without pets, dog owners with evening chronotypes had a significantly increased odds of depression (OR = 1.60, 95%CI = 1.12-2.29), whereas morning chronotypes did not (OR = 0.94, 95%CI = 0.71-1.23). Further, our data suggested that evening chronotypes benefited more from walking their dog themselves in the morning (OR = 0.75, 95%CI = 0.46-1.23, Pintx = 0.064;) than morning chronotypes.

CONCLUSIONS

Overall, dog ownership was not associated with depression risk though it was increased among evening chronotypes. Walking their dog in the morning might help evening chronotypes to lower their odds of depression, though more data are needed to confirm this finding.

The role of sleep quality and perceived stress on depressive symptoms among tertiary hospital nurses: a cross-sectional study

BACKGROUND

Nurses in tertiary hospitals are at high risk for depression. Understanding sleep quality and perceived stress may contribute to nurses' mental health and health-related nursing productivity. The aim of this study was to investigate the role of sleep quality and perceived stress on depressive symptoms among nurses in tertiary hospitals.

METHODS

A total of 2,780 nurses (overall response rate = 91.1%) were recruited through a cross-sectional survey in 23 tertiary hospitals in China. Questionnaires included the Self-Rating Depression Scale, the Pittsburgh Sleep Quality Index, and the Chinese Perceived Stress Scale. Variables that were significant in Chi-square tests were further entered into binary logistic stepwise regression.

RESULTS

The prevalence of depressive symptoms was 60.3% (n = 1,676), of which 97.4% (n = 1,633) were female, and 77.8% were younger than 35 years (n = 1,304). Nurses who had moderate, poor, severe sleep quality and poor perceived pressure were more likely to be depressed. Master's degree, 6-10 years of work, and physical activity were protective factors, while the opposite was the case for shift work and high dissatisfaction.

CONCLUSIONS

More than half of nurses working in tertiary care hospitals reported depressive symptoms, and lower sleep quality and higher perceived stress were more associated with this. Perceived stress is an interesting concept, which may provide a new entry point for the well-known idea that there is a relationship between poor sleep quality and depression. It is possible to reduce depressive symptoms among public hospital nurses by providing information on sleep health and stress relief.

Association between matched chronotype and poor mental health among shift workers: a systematic review and meta-analysis

BACKGROUND

Nearly 0.7 billion workers are involved in the shift work system, leading to concerns about its potential impacts on the large-scale population mental health. This study aimed to synthesise evidence of the associations between matched chronotype and the risk of poor mental health among shift workers.

METHODS

Six computerised databases were searched from inception to September 2022. Observational studies were selected if they reported any association between common mental health parameters and chronotype scores/types of shift workers. The Preferred Reporting Items for Systematic Reviews and Meta-analyses checklist was followed. We extracted adjusted risk estimates to calculate pooled effect sizes and explore sources of heterogeneity. The study was registered in PROSPERO: CRD42022357437.

RESULTS

Fourteen studies including 49 909 workers were identified. Ever shift workers had a higher risk of poor mental health than the day workers (pooled OR 1.15, 95% CI 1.03 to 1.28; I²=14%, p=0.29), with the evening chronotype ever shift workers having a 1.47 times higher risk than those who worked during the day (pooled OR 1.47, 95% CI 1.13 to 1.91; I²=42%, p=0.16). Sensitivity analysis excluding studies with the highest risk of bias of each group demonstrated consistent findings.

CONCLUSIONS

Evening chronotype ever shift workers have poorer mental health than shift workers with other chronotypes. Chronotype remains unrecognised in the contemporary rostering system, making it a hidden contributor to occupational mental health. Work-related physical and mental stresses may be prevented/mitigated with further investigation on optimising shift work schedule combined with individual chronotype preference.

Subjective and objective sleep and circadian parameters as predictors of depression-related outcomes: A machine learning approach in UK Biobank

BACKGROUND

Sleep and circadian disruption are associated with depression onset and severity, but it is unclear which features (e.g., sleep duration, chronotype) are important and whether they can identify individuals showing poorer outcomes.

METHODS

Within a subset of the UK Biobank with actigraphy and mental health data (n = 64,353), penalised regression identified the most useful of 51 sleep/rest-activity predictors of depression-related outcomes; including case-control (Major Depression (MD) vs. controls; postnatal depression vs. controls) and within-case comparisons (severe vs. moderate MD; early vs. later onset, atypical vs. typical symptoms; comorbid anxiety; suicidality). Best models (of lasso, ridge, and elastic net) were selected based on Area Under the Curve (AUC).

RESULTS

For MD vs. controls (n_(MD) = 24,229; n_(control) = 40,124), lasso AUC was 0.68, 95 % confidence interval (CI) 0.67-0.69. Discrimination was reasonable for atypical vs. typical symptoms (n_(atypical) = 958; n_(typical) = 18,722; ridge: AUC 0.74, 95 % CI 0.71-0.77) but poor for remaining models (AUCs 0.59-0.67). Key predictors across most models included: difficulty getting up, insomnia symptoms, snoring, actigraphy-measured daytime inactivity and lower morning activity (~8 am). In a distinct subset (n = 310,718), the number of these factors shown was associated with all depression outcomes.

LIMITATIONS

Analyses were cross-sectional and in middle-/older aged adults: comparison with longitudinal investigations and younger cohorts is necessary.

DISCUSSION

Sleep and circadian measures alone provided poor to moderate discrimination of depression outcomes, but several characteristics were identified that may be clinically useful. Future work should assess these features alongside broader sociodemographic, lifestyle and genetic features.

Association of early life physical and sexual abuse with premature mortality among female nurses: prospective cohort study

OBJECTIVE

To explore associations between early life physical and sexual abuse and subsequent risk of premature mortality (death before age 70 years).

DESIGN

Prospective cohort study.

SETTING

The Nurses' Health Study II (2001-19).

PARTICIPANTS

67 726 female nurses aged 37-54 years when completing a violence victimization questionnaire in 2001.

MAIN OUTCOME MEASURES

Hazard ratios and 95% confidence intervals for total and cause specific premature mortality by childhood or adolescent physical and sexual abuse, estimated by multivariable Cox proportional hazard models.

RESULTS

2410 premature deaths were identified over 18 years of follow-up. Nurses who experienced severe physical abuse or forced sexual activity in childhood and adolescence had a higher crude premature mortality rate than nurses without such abuse in childhood or adolescence (3.15 v 1.83 and 4.00 v 1.90 per 1000 person years, respectively). The corresponding age adjusted hazard ratios for premature deaths were 1.65 (95% confidence interval 1.45 to 1.87) and 2.04 (1.71 to 2.44), respectively, which were materially unchanged after further adjusting for personal characteristics and early life socioeconomic status (1.53, 1.35 to 1.74, and 1.80, 1.50 to 2.15, respectively). Cause specific analyses indicated that severe physical abuse was associated with a greater risk of mortality due to external causes of injury and poisoning (multivariable adjusted hazard ratio 2.81, 95% confidence interval 1.62 to 4.89), suicide (3.05, 1.41 to 6.60), and diseases of the digestive system (2.40, 1.01 to 5.68). Forced sexual activity as a child and adolescent was associated with greater risk of mortality due to cardiovascular disease (2.48, 1.37 to 4.46), external injury or poisoning (3.25, 1.53 to 6.91), suicide (4.30, 1.74 to 10.61), respiratory disease (3.74, 1.40 to 9.99), and diseases of the digestive system (4.83, 1.77 to 13.21). The association of sexual abuse with premature mortality was stronger among women who smoked or had higher levels of anxiety during adulthood. Smoking, low physical activity, anxiety, and depression each explained 3.9-22.4% of the association between early life abuse and premature mortality.

CONCLUSION

Early life physical and sexual abuse could be associated with a greater risk of adult premature mortality.

Genetics of circadian rhythms and sleep in human health and disease

Circadian rhythms and sleep are fundamental biological processes integral to human health. Their disruption is associated with detrimental physiological consequences, including cognitive, metabolic, cardiovascular and immunological dysfunctions. Yet many of the molecular underpinnings of sleep regulation in health and disease have remained elusive. Given the moderate heritability of circadian and sleep traits, genetics offers an opportunity that complements insights from model organism studies to advance our fundamental molecular understanding of human circadian and sleep physiology and linked chronic disease biology. Here, we review recent discoveries of the genetics of circadian and sleep physiology and disorders with a focus on those that reveal causal contributions to complex diseases.

Sleep's role in the development and resolution of adolescent depression

Two adolescent mental health fields - sleep and depression - have advanced largely in parallel until about four years ago. Although sleep problems have been thought to be a symptom of adolescent depression, emerging evidence suggests that sleep difficulties arise before depression does. In this Review, we describe how the combination of adolescent sleep biology and psychology uniquely predispose adolescents to develop depression. We describe multiple pathways and contributors, including a delayed circadian rhythm, restricted sleep duration and greater opportunity for repetitive negative thinking while waiting for sleep. We match each contributor with evidence-based sleep interventions, including bright light therapy, exogenous melatonin and cognitive-behaviour therapy techniques. Such treatments improve sleep and alleviate depression symptoms, highlighting the utility of sleep treatment for comorbid disorders experienced by adolescents.

Adaptation and Pilot Study of a Behavioral Intervention Targeting Morning Activation Deficits in Dementia Caregivers: Scheduling Activity and Monitoring Mornings (SAMM)

OBJECTIVES

Morning activation deficits (MADs) correlate with depression symptom persistence in older dementia caregivers. To clarify the potential of MADs as a target for depression interventions, we aimed to: 1) adapt an existing behavioral activation program, Engage therapy, to target mornings; and 2) evaluate effects on self-reported MADs and depression symptoms.

METHODS

While trialing the 9-week Engage adaption (targeting mornings) in six older dementia caregivers, we incorporated feedback and finalized an adapted program called Scheduling Activity and Monitoring Mornings (SAMM). We delivered the SAMM protocol to 13 dementia caregivers (all female; mean age = 69, standard deviation = 7). We report modifications made/rationale, as well as changes in subjective MADs (relevant items from the Composite Scale of Morningness) and depression symptoms (Patient Health Questionnaire - 9).

RESULTS

Using caregiver and expert input, we adapted the protocol to: include educational materials/content describing the potential relationship between morning inactivity and depression; target activity scheduling within 2 hours of awakening (preferably earlier); and focus only on the main components of morning activity scheduling, planning, and monitoring. This program was associated with decreases in subjective MADs averaging 29% at week 4, 52% at week 6, and 57% by week 9 (all p's <0.005). Initial depression symptoms were significantly reduced, by 62%, at week 9.

CONCLUSIONS

These preliminary findings suggest that subjective MADs can be modified pragmatically, and that doing so may have antidepressant effects. A controlled trial with measures of the putative mechanism is needed to clarify whether, and if so how, targeting MAD with SAMM causally perturbs depression's mechanisms.

The mediating effect of attachment insecurity on circadian consequences of childhood trauma

Circadian preferences have been associated with mental health as well as social and physical health in recent years. However, factors associated with circadian preferences have not been fully elucidated. The main aim of this study is to investigate the associations of childhood trauma and attachment styles with circadian preferences. A total of 673 participants were evaluated using the Morningness-Eveningness Questionnaire (MEQ), the Childhood Trauma Questionnaire 28 (CTQ-28), and the Experiences in Close Relationships-Revised (ECR-R) questionnaire. The results indicated that 14.9% (n = 100) of the participants were morning type, 20.6% (n = 139) were evening type, and 64.5% (n = 434) were intermediate type. Both childhood trauma and attachment-related anxiety/avoidance scores were associated with being evening type (p < .01). Moreover, attachment-related anxiety and avoidance fully mediated the association between childhood trauma and circadian preferences. The present study showed that attachment styles might be associated with circadian preferences. Further studies are needed to replicate these results and to infer explanatory mechanisms for these cross-sectional associations.

Primary hypothyroidism and chronotypes in adult women

Objective

Abnormal thyroid function may disrupt sleep architecture. We aimed to determine the frequency of various chronotypes in women with hypothyroidism. We performed a single-center retrospective study at an ambulatory clinic from January 2013-December 2015. Participants were women with hypothyroidism. Chronotype was determined from the Munich ChronoType Questionnaire. The χ² test was used to compare differences in clinical characteristics and sleep patterns in early and intermediate/late chronotypes. The t test was used to compare differences between means.

Results

We evaluated 99 patients (mean [SD], 56 [7] years): calculated chronotype revealed: 56% early, 38% intermediate and 6% late. Analysis with the χ² test showed significant differences between early and intermediate/late calculated chronotypes for sleep latency (P = 0.01), light exposure (P = 0.009), and no alcohol intake (P = 0.001). t test showed the following differences in mean (SD) between chronotypes: sleep duration, 7.30 (1.39) hours (early chronotype) and 7.04 (2.06) hours (intermediate/late); body mass index (BMI), 29.4 (7.3) (early) and 31.1 (6.8) (intermediate/late); and TSH level, 2.89 (3.69) mIU/L (early) and 1.69 (1.41) mIU/L (intermediate/late). Early chronotypes were frequent in women with hypothyroidism. Light exposure and BMI may influence chronotypes in patients with hypothyroidism; findings are consistent with healthier behaviors in patients who tend toward morningness.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13104-022-05934-3.

Sleep disorders and non-sleep circadian disorders predict depression: a systematic review and meta-analysis of longitudinal studies

Patients with depression often suffer from sleep disorders and non-sleep circadian disorders. However, whether they precede and predict subsequent depression is unclear. We conducted a meta-analysis of studies on sleep disorders and non-sleep circadian disorders. We found insomnia, hypersomnia, short and long sleep duration, obstructive sleep apnea, restless legs syndrome and eveningness orientation at baseline all led to subsequent depression. Those with propensity to late meal patterns, heightened levels of cortisol in awakening response and low robustness of rest-activity rhythm at baseline had higher risks for later depression. Among insomnia subtypes, difficulty initiating sleep and difficulty maintaining sleep predicted future depression. Notably, persistent insomnia at baseline contributed to more than two-fold risk of incident depression compared to insomnia. Moreover, insomnia symptom numbers showed dose-dependent relationship with the incident depression. In conclusion, different types of sleep disorders and non-sleep circadian disorders were proven to be risk factors of subsequent depression, and mechanisms underlying the relationship between sleep disorders, non-sleep circadian disorders and subsequent depression should be further elucidated in the future.

Association of Night Shift Work With Chronic Spontaneous Urticaria and Effect Modification by Circadian Dysfunction Among Workers

Purpose: Night shift work is common in the current working environment and is a risk factor for many diseases. The study aimed to explore the relationship between night shift work with chronic spontaneous urticaria (CSU), and the modification effect of circadian dysfunction on it. Methods: A cross-sectional survey was conducted among Chinese workers. Exposure was measured by night work history and duration. Circadian dysfunction was characterized by excessive daytime sleepiness (EDS). The diagnosis of CSU was made by dermatologists who were investigating on the spot. The effect size was expressed as odds ratios (ORs). Results: A total of 8,057 participants were recruited, and 7,411 (92%) with complete information were included in the final analyses. The prevalence rates of CSU for workers without night shift and those with night shift history were 0.73 and 1.28%, respectively. Compared with workers who never worked night shifts, the risk of CSU increased with the length of night shift work: OR = 1.55 (95% confidence interval [CI]: 0.78-3.06) for duration <5 years and OR = 1.91 (95% CI: 1.12-3.26) for duration ≥5 years. EDS s EDS has been shown to modify this combination. Among workers without EDS, there was no association between night shift and CSU (OR = 0.94; 95% CI: 0.49-1.79). Whereas, in participants with EDS, the correlation was significant (OR = 3.58; 95% CI: 1.14-11.20). However, the effect modification by sleep disturbance was not observed. Conclusions: Night shift work is a risk factor for CSU, and there is a dose-response relationship between night shift work hours and the risk of CSU. This connection may be modified by circadian dysfunction.

Using Mendelian Randomisation methods to understand whether diurnal preference is causally related to mental health

Late diurnal preference has been linked to poorer mental health outcomes, but the understanding of the causal role of diurnal preference on mental health and wellbeing is currently limited. Late diurnal preference is often associated with circadian misalignment (a mismatch between the timing of the endogenous circadian system and behavioural rhythms), so that evening people live more frequently against their internal clock. This study aims to quantify the causal contribution of diurnal preference on mental health outcomes, including anxiety, depression and general wellbeing and test the hypothesis that more misaligned individuals have poorer mental health and wellbeing using an actigraphy-based measure of circadian misalignment. Multiple Mendelian Randomisation (MR) approaches were used to test causal pathways between diurnal preference and seven well-validated mental health and wellbeing outcomes in up to 451,025 individuals. In addition, observational analyses tested the association between a novel, objective measure of behavioural misalignment (Composite Phase Deviation, CPD) and seven mental health and wellbeing outcomes. Using genetic instruments identified in the largest GWAS for diurnal preference, we provide robust evidence that early diurnal preference is protective for depression and improves wellbeing. For example, using one-sample MR, a twofold higher genetic liability of morningness was associated with lower odds of depressive symptoms (OR: 0.92, 95% CI: 0.88, 0.97). It is possible that behavioural factors including circadian misalignment may contribute in the chronotype depression relationship, but further work is needed to confirm these findings.

Seasonal variations in sleep duration and sleep complaints: A Swedish cohort study in middle-aged and older individuals

Subjective sleep reports are widely used research tools in epidemiology. Whether sleep reports can differ between seasons is less clear. Using multivariable binary or multinomial logistic regression analyses, in the present Swedish cross-sectional two-centre cohort study (N = 19,254; mean age 61 years), we found that participants surveyed during the summer (June-August) were more likely to report short sleep duration (defined as ≤ 6 hr) compared with those interviewed during the autumn (odds ratio [95% confidence interval] = 1.14 [1.04-1.25]). Individuals interviewed in the winter (December-February) were less likely to report early awakenings compared with participants surveyed in the autumn (September-November; odds ratio [95% confidence interval] = 0.85 [0.75-0.96]). Complaints of difficulties in falling asleep and disturbed sleep were less common among participants interviewed during spring (March-May) compared with those interviewed during the autumn (odds ratio [95% confidence interval] = 0.86 [0.74-0.99] and 0.88 [0.79-0.98], respectively). No seasonal variations in reports of long sleep, difficulty maintaining sleep, or feeling not rested after sleep were observed. Additional subgroup analysis revealed that summer participants were more likely to report short sleep duration and early morning awakenings than individuals surveyed in winter. In conclusion, this Swedish study indicates that self-reported sleep characteristics may vary across seasons. Further studies are needed to confirm our findings.

Genetically Proxied Diurnal Preference, Sleep Timing, and Risk of Major Depressive Disorder

Importance

Morning diurnal preference is associated with reduced risk of major depressive disorder (MDD); however, causality in this association is uncertain.

Objective

To examine the association of genetically proxied morning diurnal preference with depression risk using mendelian randomization.

Design, Setting, and Participants

This 2-sample mendelian randomization study used summary-level genetic associations with diurnal preference and MDD. Up to 340 genetic loci associated with diurnal preference in a meta-analysis of the UK Biobank and 23andMe cohorts were considered as genetic proxies for diurnal preference. The effect size of these variants was scaled using genetic associations with accelerometer-based measurement of sleep midpoint. Genetic associations with MDD were obtained from a meta-analysis of genome-wide association studies data from the Psychiatric Genomics Consortium and UK Biobank. The inverse-variance weighted method was used to estimate the association of genetically proxied morning diurnal preference, corresponding to a 1-hour earlier sleep midpoint, with MDD risk.

Exposures

Morning diurnal preference scaled to a 1-hour earlier, objectively measured sleep midpoint.

Main Outcomes and Measures

Risk of MDD, including self-reported and clinically diagnosed cases, as ascertained in meta-analyses of genome-wide association studies.

Results

A total of 697 828 individuals (all of European ancestry) were in the UK Biobank and 23andMe cohorts; 85 502 in the UK Biobank had measurements of the sleep midpoint. A further 170 756 individuals with MDD and 329 443 control participants (all of European ancestry) were in the Psychiatric Genomics Consortium and UK Biobank data. Genetically proxied earlier diurnal preference was associated with a 23% lower risk of depression (odds ratio [OR] per 1-hour earlier sleep midpoint, 0.77 [95% CI, 0.63-0.94]; P = .01). This association was similar when restricting analysis to individuals with MDD as stringently defined by the Psychiatric Genomics Consortium (OR, 0.73 [95% CI, 0.54-1.00]; P = .05) but not statistically significant when defined by hospital-based billing codes in the UK Biobank (OR, 0.64 [95% CI, 0.39-1.06]; P = .08). Sensitivity analyses examining potential bias due to pleiotropy or reverse causality showed similar findings (eg, intercept [SE], 0.00 [0.001]; P = .66 by Egger intercept test).

Conclusions and Relevance

The results of this mendelian randomization study support a protective association of earlier diurnal preference with risk of MDD and provide estimates contextualized to an objective sleep timing measure. Further investigation in the form of randomized clinical trials may be warranted.

The Mechanism of Oral Melatonin Ameliorates Intestinal and Adipose Lipid Dysmetabolism Through Reducing Escherichia Coli-Derived Lipopolysaccharide

BACKGROUND & AIMS

Gut microbiota have been reported to be sensitive to circadian rhythms and host lipometabolism, respectively. Although melatonin-mediated beneficial efforts on many physiological sites have been revealed, the regulatory actions of oral melatonin on the communication between gut microbiota and host are still not clear. Angiopoietin-like 4 (ANGPTL4) has been shown to be strongly responsible for the regulation of systemic lipid metabolism. Herein, we identified that oral melatonin improved lipid dysmetabolism in ileum and epididymal white adipose tissue (eWAT) via gut microbiota and ileac ANGPTL4.

METHODS

Analyses of jet-lag (JL) mice, JL mice with oral melatonin administration (JL+MT), and the control for mRNA and protein expression regarding lipid uptake and accumulation in ileum and eWAT were made. Gut microbiome sequencing and experimental validation of target strains were included. Functional analysis of key factors/pathways in the various rodent models, including the depletion of gut microbiota, mono-colonization of Escherichia coli, and other genetic intervention was made. Analyses of transcriptional regulation and effects of melatonin on E coli-derived lipopolysaccharide (LPS) in vitro were made.

RESULTS

JL mice have a higher level of ileal lipid uptake, fat accumulation in eWAT, and lower level of circulating ANGPTL4 in comparison with the control mice. JL mice also showed a significantly higher abundance of E coli and LPS than the control mice. Conversely, oral melatonin supplementation remarkably reversed these phenotypes. The test of depletion of gut microbiota further demonstrated that oral melatonin-mediated improvements on lipometabolism in JL mice were dependent on the presence of gut microbiota. By mono-colonization of E coli, LPS has been determined to trigger these changes similar to JL. Furthermore, we found that LPS served as a pivotal link that contributed to activating toll-like receptor 4 (TLR4)/signal transducer and activator of transcription 3 (STAT3_/REV-ERBα) signaling to up-regulate nuclear factor interleukin-3-regulated protein (NFIL3) expression, resulting in increased lipid uptake in ileum. In MODE-K cells, the activation of NFIL3 has further been shown to inhibit ANGPTL4 transcription, which is closely associated with lipid uptake and transport in peripheral tissues. Finally, we confirmed that melatonin inhibited LPS via repressing the expression of LpxC in E coli.

CONCLUSIONS

Overall, oral melatonin decreased the quantity of E coli-generated LPS, which alleviated NFIL3-induced transcriptional inhibition of ANGPTL4 through TLR4/IL-22/STAT3 signaling in ileum, thereby resulting in the amelioration of ileal lipid intake and lower fat accumulation in eWAT. These results address a novel regulation of oral melatonin originating from gut microbiota to host distal tissues, suggesting that microbe-generated metabolites are potential therapies for melatonin-mediated improvement of circadian rhythm disruption and related metabolic syndrome.

Association of chronotype as assessed by the midpoint of sleep with the dietary intake and health-related quality of life for elderly Japanese women

The relationship of chronotype differences with dietary habits and health-related outcomes among elderly people is not fully understood, although sex and generation differences are observed in human chronotype. Accordingly, we analysed the association of chronotype (as assessed by the midpoint of sleep) with dietary intake and health-related quality of life (HRQoL) in elderly Japanese women. The subjects in this cross-sectional study were 1618 women aged 65 years and older who were grandmothers or acquaintances of dietetics students. The subjects were classified into quintiles with respect to the midpoint of sleep, from the earliest to the latest quintile. HRQoL was assessed by the Japanese version of the short-form 36-item health survey score. Mental health was assessed by the Center for Epidemiologic Studies Depression (CES-D) Scale. Dietary intake was assessed by a brief-type self-administered diet history questionnaire. A later midpoint of sleep was associated with a lower intake of vitamin D and a higher intake of bread and caffeinated drinks. No correlations were observed between chronotype and other nutrient and food intake. The subjects with a late midpoint of sleep (eveningness) showed poor general health perception (GH) and high CES-D scores. Other HRQoL scores did not differ among groups with different midpoints of sleep. In conclusion, chronotype as assessed by the midpoint of sleep is associated with poor GH and depressive tendencies in elderly Japanese women. Additionally, a few associations were found between dietary intake and chronotype in elderly Japanese women.

Evaluating the timing of differences in activity related to depression symptoms across adulthood in the United States

BACKGROUND

Relative activity deficits found in people with (verses without) depression symptoms/disorders may accumulate uniformly throughout the day, or they may tend to be expressed at specific times. Evidence for the latter would suggest times when behavioral approaches are most needed to reduce depression and its health consequences.

METHODS

We performed a secondary-data analysis of participants who contributed valid accelerometer data at the 2005-2006 National Health and Nutrition Examination Survey (n=4390). Participants were categorized according to the Patient Health Questionnaire-9 standard cut-point of ≥10 (i.e., people with versus without clinically significant depression symptoms). Average levels of accelerometer-measured activity in two-hour bins were the dependent variable in mixed models testing if the relationship between depression status and activity level differed by time of day; and if any such relations varied by age group (18-29 years, 30-44 years, 45-59 years, and 60+ years).

RESULTS

In adults over the age of 30, people with depression symptoms had generally lower levels of activity across the day, but these effects were most markedly pronounced in the morning hours. We found no differences in activity levels associated with prevalent depression symptoms among people 18-30 years of age.

LIMITATIONS

Core aspects of depression pathophysiology that produce these different activity patterns and confer their effects on mood were not measured.

CONCLUSIONS

In adults 30 years and older, efforts to ameliorate relative activity deficits associated with depression may benefit from considering the apparently outsized role of inactivity that occurs in the morning.

Associations of sleep phenotypes with severe intentional self-harm: a prospective analysis of the UK Biobank cohort

STUDY OBJECTIVES

We aimed to investigate the prospective associations of sleep phenotypes with severe intentional self-harm (ISH) in middle-aged and older adults.

METHODS

A total of 499,159 participants (mean age: 56.55 ± 8.09 years; female: 54.4%) were recruited from the UK Biobank between 2006 and 2010 with follow-up until February 2016 in this population-based prospective study. Severe ISH was based on hospital inpatient records or a death cause of ICD-10 codes X60-X84. Patients with hospitalized diagnosis of severe ISH before the initial assessment were excluded. Sleep phenotypes, including sleep duration, chronotype, insomnia, sleepiness, and napping, were assessed at the initial assessments. Cox regression analysis was used to estimate temporal associations between sleep phenotypes and future risk of severe ISH.

RESULTS

During a follow-up period of 7.04 years (SD: 0.88), 1,219 participants experienced the first hospitalization or death related to severe ISH. After adjusting for demographics, substance use, medical diseases, mental disorders, and other sleep phenotypes, short sleep duration (HR: 1.50, 95% CI: 1.23-1.83, P < .001), long sleep duration (HR: 1.56, 95% CI: 1.15-2.12, P = .004), and insomnia (usually: HR: 1.57, 95% CI: 1.31-1.89, P < .001) were significantly associated with severe ISH. Sensitivity analyses excluding participants with mental disorders preceding severe ISH yielded similar results.

CONCLUSION

The current study provides the empirical evidence of the independent prediction of sleep phenotypes, mainly insomnia, short and long sleep duration, for the future risk of severe ISH among middle-aged and older adults.

Menstrual cycle regularity and length across the reproductive lifespan and risk of premature mortality: prospective cohort study

OBJECTIVE

To evaluate whether irregular or long menstrual cycles throughout the life course are associated with all cause and cause specific premature mortality (age <70 years).

DESIGN

Prospective cohort study.

SETTING

Nurses' Health Study II (1993-2017).

PARTICIPANTS

79 505 premenopausal women without a history of cardiovascular disease, cancer, or diabetes and who reported the usual length and regularity of their menstrual cycles at ages 14-17 years, 18-22 years, and 29-46 years.

MAIN OUTCOME MEASURES

Hazard ratios and 95% confidence intervals for all cause and cause specific premature mortality (death before age 70 years) were estimated from multivariable Cox proportional hazards models.

RESULTS

During 24 years of follow-up, 1975 premature deaths were documented, including 894 from cancer and 172 from cardiovascular disease. Women who reported always having irregular menstrual cycles experienced higher mortality rates during follow-up than women who reported very regular cycles in the same age ranges. The crude mortality rate per 1000 person years of follow-up for women reporting very regular cycles and women reporting always irregular cycles were 1.05 and 1.23 for cycle characteristics at ages 14-17 years, 1.00 and 1.37 for cycle characteristics at ages 18-22 years, and 1.00 and 1.68 for cycle characteristics at ages 29-46 years. The corresponding multivariable adjusted hazard ratios for premature death during follow-up were 1.18 (95% confidence interval 1.02 to 1.37), 1.37 (1.09 to 1.73), and 1.39 (1.14 to 1.70), respectively. Similarly, women who reported that their usual cycle length was 40 days or more at ages 18-22 years and 29-46 years were more likely to die prematurely than women who reported a usual cycle length of 26-31 days in the same age ranges (1.34, 1.06 to 1.69; and 1.40, 1.17 to 1.68, respectively). These relations were strongest for deaths related to cardiovascular disease. The higher mortality associated with long and irregular menstrual cycles was slightly stronger among current smokers.

CONCLUSIONS

Irregular and long menstrual cycles in adolescence and adulthood are associated with a greater risk of premature mortality (age <70 years). This relation is slightly stronger among women who smoke.

Timing of Daily Activities over a 24-Hour Period and Affective Status among a National Cohort of Older Dementia Caregivers

Objective: To examine the allocation of daily activities over a 24-hour period in caregivers (CGs) with and without a probable affective disorder. Methods: Participants were 192 older dementia CGs (mean age = 72.9 years, 70% female) who participated in the National Study of Caregiving. Time diary data were used to measure the duration and timing that caregivers were doing hygienic self-care, eating/drinking, household care, physical caregiving, medical caregiving, socializing, and television viewing. Affective status was assessed using the two-item Patient Health Questionnaire and the Generalized Anxiety Disorder screeners. Results: CGs were more likely to screen positive for depression/anxiety symptoms if they started hygienic self-care later (OR = 1.76, 95% CI = 1.10-2.83) and started medical caregiving later (OR = 2.34, 95% CI = 1.24-4.41). Hygienic self-care start times attenuated the effects of medical caregiving on the affective status. Discussion: Later timing of hygienic self-care may be an important behavioral response that contributes to affective disorder risk in dementia CGs.

Resting-State Function Connectivity Associated With Being a "Morning-Type" Dementia Caregiver and Having Lower Depression Symptom Severity

OBJECTIVES

A lack of "morningness" predicts greater depression symptom severity over time, including in a vulnerable group of older adults: family dementia caregivers (dCGs). Evidence regarding the neurobiological basis of these correlations is needed to guide future research towards biomarker-informed detection and prevention approaches. We therefore primarily aimed to identify simple resting-state biomarkers that correlated with a lack of "morningness" in dCGs.

METHOD

We examined 54 dCGs (mean age = 70, range: 61-84; 70% female) of whom 40% were definite "morning types" according to Composite Scale of Morningness (CSM). Using a 7 Tesla resting-state sequence, we compared the functional connectivity of nodes in networks previously implicated in depression (fronto-parietal, default mode, limbic, and salience) between caregivers who were and were not "morning types."

RESULTS

Correcting for voxel-wise comparisons, "morning-type" dCGs had less amygdala-posterior cingulate connectivity (Cohen's d = -1.3), which statistically mediated ~32% of the association between the degree of "morningness" and lower depression severity. Post hoc analyses of CSM items found significant correlations, with both amygdala-posterior cingulate FC and depression severity, for 4/6 items pertaining to difficulty, 2/5 items pertaining to preference, and 0/2 items pertaining to typical patterns.

DISCUSSION

Prior research shows that amygdala-posterior cingulate connectivity increases when allocating attention to peripheral aspects of negative emotional stimuli. As such, difficulty with morning activation may relate to the ongoing direction of focus around distressing content; in contrast, morning activity participation may serve to limit focus on distress. Replication and experimental studies are required to confirm these associations and their modifiability.

The association between shift patterns and the quality of hand antisepsis in a neonatal intensive care unit: An observational study

BACKGROUND

Healthcare-associated infections represent a major burden in neonatal intensive care units. Hand antisepsis is the most important tool for prevention, however, compliance among healthcare workers remains low.

OBJECTIVES

To prospectively evaluate the influence of different work shifts (extended working hours, night shifts) on the quality of healthcare workers' hand antisepsis.

DESIGN

Observational study.

SETTINGS

Two equivalent "Level III" neonatal intensive care units at the University Hospital Vienna, Austria.

PARTICIPANTS

Seventy healthcare workers, 46 nurses and 24 physicians.

METHODS

The Semmelweis Scanner, an innovative training device assessing the quality of hand antisepsis with an ultraviolet dye labelled alcohol-based hand rub, was employed to collect data on the hand surface coverage achieved during hand antisepsis of participants. It provides visual feedback of appropriately versus inappropriately disinfected areas of the hand and can also be used for the objective quantification of hand surface coverage with the hand rub. Measurements were performed before and after 12.5 h (h) day and night shifts (nurses), as well as before and after regular 8 h day shifts and extended 25 h shifts (physicians). To avoid any bias caused by residual ultraviolet marker, scans had to be separated by 24 h periods. Primary outcome was the hand surface coverage with the hand rub: Hand scans were categorized as "passed" if an appropriate quality of hand hygiene, defined as a minimum 97% coverage of hand surface, was achieved. A generalized mixed model was used to analyse the data accounting for repeated measurements.

RESULTS

Seventy healthcare workers performed a total of 485 scans. Nineteen scans had to be excluded, resulting in 466 scans for further analyses. A difference in the predicted probability of achieving appropriate hand antisepsis was found between the beginning and end of extended shifts: In physicians, adequate hand antisepsis was remarkably reduced after 25 h shifts (predicted probability 99.4% vs 78.8%), whereas there was no relevant difference between the beginning and end of 8 h day shifts (92.2% vs 97.3%). In nurses, a relevant difference was found between the beginning and end of 12.5 h day shifts (88.6% vs 73.6%). This difference was not found for 12.5 h night shifts. The most frequently missed area on the hands was the right dorsum.

CONCLUSION

The quality of hand antisepsis of healthcare workers in neonatal intensive care units may be associated with long working hours.

Nocturnal heart rate variability moderates the association between sleep-wake regularity and mood in young adults

STUDY OBJECTIVES

Sleep-wake regularity (SWR) is often disrupted in college students and mood disorders are rife at this age. Disrupted SWR can cause repetitive and long-term misalignment between environmental and behavioral cycles and the circadian system which may then have psychological and physical health consequences. We tested whether SWR was independently associated with mood and autonomic function in a healthy adult cohort.

METHODS

We studied 42 college students over a 3 week period using daily sleep-wake diaries and continuous electrocardiogram recordings. Weekly SWR was quantified by the interdaily stability of sleep-wake times (ISSW) and mood was assessed weekly using the Beck Depression Inventory-II. To assess autonomic function, we quantified the high-frequency (HF) power of heart rate variability (HRV). Linear mixed effects models were used to assess the relationship between repeated weekly measures of mood, SWR, and HF.

RESULTS

Low weekly ISSW predicted subsequent poor mood and worsening mood independently of age, sex, race, sleep duration, and physical activity. Although no association was found between ISSW and HF, the ISSW-mood association was significantly moderated by nocturnal HF, i.e. reported mood was lowest after a week with low ISSW and high HF. Prior week mood scores did not significantly predict the subsequent week's ISSW.

CONCLUSIONS

Irregular sleep-wake timing appears to precede poor mood in young adults. Further work is needed to understand the implications of high nocturnal HRV in those with low mood and irregular sleep-wake cycles.

A composite measure of sleep health is associated with symptoms of depression among Japanese female hospital nurses

BACKGROUND

Individual dimensions of sleep health, including satisfaction, sleepiness/alertness, timing, efficiency, and duration, are associated with depression. We investigated whether a composite sleep health score is associated with symptoms of depression among Japanese female hospital nurses.

METHODS

Participants were nurses (n = 2482, all women, age 31.2 ± 8.9 years) working at three general hospitals in Tokyo, Japan. A cross-sectional survey, conducted in 2015, assessed self-reported sleep and symptoms of depression. Sleep health was categorized as "good" or "poor" across five dimensions: satisfaction, daytime sleepiness, mid-sleep time, efficiency, and duration. A composite sleep health score was calculated by summing the number of "poor" dimensions. Depression was defined by depressed mood, loss of interest, or at least one of those symptoms ("depression symptoms"). Associations between sleep health and symptoms of depression were evaluated with multivariate logistic regression analyses, adjusting for sociodemographic factors and hypnotic medication use.

RESULTS

In multivariate logistic regression analyses, sleep health symptoms of poor satisfaction, efficiency, and duration were significantly associated with depressed mood; daytime sleepiness and poor efficiency were significantly associated with loss of interest; and poor satisfaction, daytime sleepiness, mid-sleep time, and efficiency were significantly associated with having at least one depressive symptom. The composite sleep health score was associated in a graded fashion with greater odds of depression symptoms.

CONCLUSION

Individual and composite sleep health scores were associated with symptoms of depression. Assessing composite measures of multidimensional sleep health may help to better understand the well-known associations between poor sleep and depression and lead to improved intervention strategies.

Delayed sleep timing and circadian rhythms in pregnancy and transdiagnostic symptoms associated with postpartum depression

Later sleep timing, circadian preference, and circadian rhythm timing predict worse outcomes across multiple domains, including mood disorders, substance use, impulse control, and cognitive function. Disturbed sleep is common among pregnant and postpartum women. We examined whether sleep timing during third trimester of pregnancy predicted postpartum symptoms of mania, depression, and obsessive-compulsive disorder (OCD). Fifty-one women with a previous, but not active, episode of unipolar or bipolar depression had symptoms evaluated and sleep recorded with wrist actigraphy at 33 weeks of gestation and 2, 6, and 16 weeks postpartum. Circadian phase was measured in a subset of women using salivary dim light melatonin onset (DLMO). We divided the sample into "early sleep" and "late sleep" groups using average sleep onset time at 33 weeks of gestation, defined by the median-split time of 11:27 p.m. The "late sleep" group reported significantly more manic and depressive symptoms at postpartum week 2. Longer phase angle between DLMO and sleep onset at 33 weeks was associated with more manic symptoms at postpartum week 2 and more obsessive-compulsive symptoms at week 6. Delayed sleep timing in this sample of at-risk women was associated with more symptoms of mania, depression, and OCD in the postpartum period. Sleep timing may be a modifiable risk factor for postpartum depression.

Prevalence of shift work disorder among hospital personnel: A cross-sectional study using objective working hour data

The prevalence of shift work disorder (SWD) has been studied using self-reported data and the International Classification of Sleep Disorders, Second Edition (ICSD-2) criteria. We examined the prevalence in relation to ICSD-2 and ICSD-3 criteria, work schedules and the number of non-day shifts (work outside 06:00-18:00 hours) using objective working-hours data. Secondly, we explored a minimum cut-off for the occurrence of SWD symptoms. Hospital shift workers without (n = 1,813) and with night shifts (n = 2,917) and permanent night workers (n = 84) answered a survey (response rate 69%) on SWD and fatigue on days off. The prevalence of SWD was calculated for groups with ≥1, ≥3, ≥5 and ≥7 monthly non-day shifts utilizing the working hours registry. ICSD-3-based SWD prevalence was 2.5%-3.7% (shift workers without nights), 2.6%-9.5% (shift workers with nights) and 6.0% (permanent night workers), depending on the cut-off of non-day shifts (≥7-1/month, respectively). The ICSD-2-based prevalence was higher: 7.1%-9.2%, 5.6%-33.5% and 16.7%, respectively. The prevalence was significantly higher among shift workers with than those without nights (p-values <.001) when using the cut-offs of ≥1-3 non-day shifts. Shift workers with nights who had ≥3 days with ICSD-3-based SWD symptoms/month more commonly had fatigue on days off (49.3%) than those below the cut-off (35.8%, p < .05). The ICSD-3 criteria provided lower estimates for SWD prevalence than ISCD-2 criteria, similarly to exclusion of employees with the fewest non-day shifts. The results suggest that a plausible cut-off for days with ICSD-3-based SWD symptoms is ≥3/month, resulting in 3%-6% prevalence of SWD.

Night shift work before and during pregnancy in relation to depression and anxiety in adolescent and young adult offspring

We investigated the relationship between maternal history of nightshift work before and shift work during pregnancy and offspring risk of depression and anxiety, among mothers participating in the Nurses Health Study II and in their offspring enrolled in the Growing Up Today Study 2 between 2004 and 2013. Case definitions were based on offspring self-reports of physician/clinician-diagnosed depression and/or anxiety, regular antidepressant use and depressive symptoms assessed using the Center for Epidemiologic Studies Depression Scale. Multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using generalized estimating equation models. We found no associations between maternal nightshift work before pregnancy or during pregnancy and offspring mental health disorders (e.g., nightshift work before pregnancy: depression (based on physician/clinician diagnosis): OR_{ever nightwork}= 1.14; 95% CI, 0.88-1.47; either depression or anxiety: OR_{ever nightwork}= 0.93; 95% CI, 0.81-1.08; nightshift work during pregnancy: depression: OR_{ever nightwork}= 1.14; 95% CI, 0.68-1.94; depression or anxiety: OR_{ever nightwork}=1.17; 95% CI, 0.70-1.98) and no dose-response relationship with longer history of nightshift work (all P_Trend>0.10). Stratifying by maternal chronotype revealed a higher risk of depression for offspring whose mothers worked nightshifts before pregnancy and reported being definite morning chronotypes (a proxy for circadian strain) (OR_{ever nightwork}= 1.95; 95% CI, 1.17, 3.24 vs. OR_{ever nightwork}= 0.93; 95% CI, 0.68, 1.28 for any other chronotype; P_Interaction= 0.03). Further studies replicating our findings and refined understanding regarding the interplay of nightshift work and chronotype and its potential influences on offspring mental health are needed.

The Influence of Chronotype and Working Condition on Sleep Status and Health Related Quality of Life of Daytime Office Workers

Several companies in Japan introduced early working conditions (including recommendations on early morning work and prohibitions on nighttime overtime work) to decrease the number of long working hours at night. Nevertheless, individuals possess their own chronotype, i.e., their behavioral timing preference-be it morning or evening-that is associated with worker health. The purpose of this study was to investigate the influence of chronotype and working conditions on sleep and health related quality of life (HRQOL) using 126 daytime office workers who were classified as morning or evening type by their Morningness-Eveningness Questionnaire scores. We then compared morning and evening type workers' sleep variables (sleep onset/offset time and total sleep time), sleep quality (using the Japanese version of the Pittsburgh Sleep Quality Index), and HRQOL scores. Additionally, we compared the same sleep variables, sleep quality, and HRQOL scores of each chronotype category of worker under early and normal working conditions. As the results, evening type workers had late sleep onset/offset time, poor sleep quality, and low HRQOL (role-social component) compared to morning type workers. Furthermore, the evening type workers under early working conditions had earlier sleep onset/offset time and poorer sleep quality compared to those workers under normal working conditions. These results suggest that evening type workers in general have poor sleep and low HRQOL and those same workers under early working conditions, in particular, are associated with poor sleep quality. Therefore, in order to optimize worker health, we suggest that working conditions should be taken account of individual chronotypes.

Clocks in the clinic: circadian rhythms in health and disease

Circadian rhythms are endogenously generated recurring patterns of around 24 hours with well-established roles in physiology and behaviour. These circadian clocks are important in both the aetiology and treatment of various psychiatric and metabolic diseases. To maintain physiological homeostasis and optimal functioning, living life synchronised to these clocks is desirable; modern society, however, promotes a '24/7' lifestyle where activity often occurs during the body's 'biological night', resulting in mistimed sleep and circadian misalignment. This circadian desynchrony can increase the risk of disease and can also influence treatment response. Clinicians should be aware of the influence that circadian desynchrony can have on health and disease, in order to potentially develop new therapeutic strategies and to incorporate chronotherapeutics into current treatment strategies to enhance their utility.

More evening preference is positively associated with systemic inflammation in prediabetes and type 2 diabetes patients

Currently it is not known whether morningness-eveningness preference in non-night shift working population is associated with systemic inflammation. This study investigated the relationship between morningness-eveningness and systemic inflammation, as measured by high-sensitivity C-reactive protein (hs-CRP) in 163 non-night shift working patients with abnormal glucose tolerance (86 type 2 diabetes and 77 prediabetes). Morningness-eveningness was assessed by Composite Scale of Morningness, and participants were screened for Obstructive sleep apnea (OSA). Sleep duration, efficiency, and variability were obtained using actigraphy, and depressive symptoms and dietary patterns were also captured. Participants' mean age was 54.7 ± 10.4 years and median hs-CRP was 1.39 (interquartile range 0.82, 3.33) mg/L. More evening preference was significantly associated with higher natural log transformed (ln) hs-CRP (B = -0.051, p = 0.001). Diabetes status, glycemic control, OSA severity, sleep duration, caloric consumption and timing were not related to hs-CRP. After adjusting for age, sex, body mass index, depressive symptoms, sleep efficiency, sleep variability, percentage of daily caloric intake from protein, and statin use, more evening preference was independently associated with higher ln hs-CRP (B = -0.032, p = 0.014). In summary, in non-night shift working patients with abnormal glucose tolerance, more evening preference was independently associated with higher systemic inflammation. This finding underscore the importance of circadian regulation on cardiovascular health.