Sleep and Human Aging

Glymphatic system dysfunction in adult ADHD: Relationship to cognitive performance

OBJECTIVES

While attention-deficit/hyperactivity disorder (ADHD) persists into adulthood, the relationship between glymphatic system function and cognitive performance in adult ADHD remains unclear. This study investigated the association between glymphatic system markers and cognitive outcomes in adults with ADHD.

METHODS

This case-control study includes 41 adults with ADHD and 108 age-matched healthy controls (HCs). Glymphatic function was evaluated using choroid plexus volume (CPV), diffusion tensor imaging along the perivascular space (DTI-ALPS) index and coupling between blood‑oxygen-level-dependent signals and cerebrospinal fluid signals (BOLD-CSF coupling). Cognitive performance was measured using standardized neuropsychological tests.

RESULTS

Compared with HCs, adults with ADHD exhibited significantly lower bilateral and whole-brain ALPS indices (P < 0.05). Although CPV was increased in the ADHD group, this difference did not reach statistical significance, and no significant differences were observed in BOLD-CSF coupling between the two groups. Furthermore, whole-brain ALPS indices were positively associated with visual memory performance (r = 0.422, P = 0.005), an effect that was more pronounced in the right hemisphere (r = 0.458, P = 0.002).

LIMITATIONS

The cross-sectional design limits causal inferences, and the effects of medication were not fully accounted for.

CONCLUSIONS

These findings identify an association between glymphatic dysfunction and cognitive impairment in adults with ADHD. The observed correlation suggests that alterations in glymphatic function may underlie ADHD-related cognitive deficits. Targeting these pathways could provide novel therapeutic opportunities in the management of adult ADHD.

Psychological Interventions for Sleep Problems Among Medical and Paramedical Students: A Systematic Review

Sleep problems such as poor sleep quality and insomnia are common issues among medical and paramedical students, which may lead to mental health disorders and impaired academic performance. Despite the availability of different sleep programs and psychological interventions, as well as a few reviews exploring their effects on sleep variables in college students, a systematic review comparing their effectiveness in medical students is still lacking. This systematic review aims to investigate psychological interventions to improve sleep quality and address sleep problems in medical students. Four databases (PubMed, SciDirect, Scopus, and PsycNet) were searched to retrieve original research articles written in English and published from January 1, 2000, to September 30, 2023. Outcome measures were sleep quality, insomnia, sleep behavior, sleep quantity, and sleep-related problems. A total of 19 articles met the inclusion criteria, and 4 categories of interventions were identified (1) sleep hygiene, (2) cognitive behavioral therapy (CBT), (3) a combination of sleep hygiene/CBT with other modalities, and (4) other psychotherapeutic interventions such as progressive muscle relaxation, hypnotherapy, aromatherapy yoga, and mindfulness. Ten studies were randomized control trials, two were quasi-experimental, and the remaining seven were pre- and post-intervention designs (one group only and no control). Overall, both individual CBT and sleep hygiene education led to significant improvement in sleep quality and sleep problems among medical students, but CBT was more effective with consistent positive effects on sleep quality. Nevertheless, significant improvements in sleep quality and sleep-related outcomes were observed in studies combining these psychological interventions. Effective comparisons were limited due to the substantial heterogeneity between the studies. Further research is required to elucidate the type of psychological intervention, optimal mode of delivery, duration, and number of contacts of these interventions, including the moderators to improve sleep quality among medical students.

A sensor-based study on the environmental determinants of sleep in older adults

INTRODUCTION

The residential environment is hypothesized to influence sleep quality within urban settings. Factors associated with the residential environment include air and noise pollution, area socioeconomic status, green and blue spaces, and other neighborhood features. This study seeks to quantify the association of selected environmental factors with sleep quality in the daily lives of 211 older adults residing in the Paris metropolitan area with sensor-based methods.

METHODS

Participants' sleep and physical activity were monitored over a 7-day period using 2 accelerometers. Ecological momentary assessment (EMA) surveys were administered 4 times a day to assess depressive and anxiety symptoms. Environmental factors surrounding participants residential addresses, including noise and air pollution, walkability, green and blue space availability, median income, and population density, were computed using geoprocessing methods. Hierarchical mixed models with a random intercept at the individual level were fitted to estimate the adjusted association between residential environmental factors and sleep outcomes [total sleep time (TST), sleep efficiency (SE), and wake after sleep onset (WASO)]. Potential effect modification of or mediation by physical activity and depression and anxiety levels were explored in the analyses.

RESULTS

We observed an effect size of 1.4 more minutes of sleep for each increase of one thousand euro in neighborhood median income (Confidence Intervals: 0.35, 2.45). The average adjusted difference in total sleep time between the 10th and 90th percentiles of neighborhood median income was 23.6 minutes of sleep. Other environmental factors and depression and anxiety levels did not exhibit correlations with sleep outcomes.

CONCLUSIONS

The results reveal a positive association between median income at the residential level and TST, while no associations were identified for SE and WASO. In conclusion, these findings underscore the impact of neighborhood socioeconomic status on total sleep time within the context of urban living, highlighting the need for further research.

SleepEEGpy: a Python-based software integration package to organize preprocessing, analysis, and visualization of sleep EEG data

Sleep research uses electroencephalography (EEG) to infer brain activity in health and disease. Beyond standard sleep scoring, there is growing interest in advanced EEG analysis that requires extensive preprocessing to improve the signal-to-noise ratio and specialized analysis algorithms. While many EEG software packages exist, sleep research has unique needs (e.g., specific artifacts, event detection). Currently, sleep investigators use different libraries for specific tasks in a 'fragmented' configuration that is inefficient, prone to errors, and requires the learning of multiple software environments. This complexity creates a barrier for beginners. Here, we present SleepEEGpy, an open-source Python package that simplifies sleep EEG preprocessing and analysis. SleepEEGpy builds on MNE-Python, PyPREP, YASA, and SpecParam to offer an all-in-one, beginner-friendly package for comprehensive sleep EEG research, including (i) cleaning, (ii) independent component analysis, (iii) sleep event detection, (iv) spectral feature analysis, and visualization tools. A dedicated dashboard provides an overview to evaluate data and preprocessing, serving as an initial step prior to detailed analysis. We demonstrate SleepEEGpy's functionalities using overnight high-density EEG data from healthy participants, revealing characteristic activity signatures typical of each vigilance state: alpha oscillations in wakefulness, spindles and slow waves in NREM sleep, and theta activity in REM sleep. We hope that this software will be adopted and further developed by the sleep research community, and constitute a useful entry point tool for beginners in sleep EEG research.

Understanding Factors Associated With Sleep Quality in Korean American Older Adults Residing in Subsidized Senior Housing

PURPOSE

Sleep quality is crucial for older adults, yet many experience poor sleep due to physical, mental, and social factors. The current study addresses the research gap on sleep quality among Korean American older adults in senior housing by examining relevant factors.

METHOD

Using data from 314 Korean American residents in Los Angeles senior housing, we conducted descriptive analysis and logistic regression models.

RESULTS

Poor sleep was significantly associated with poor physical health (odds ratio [OR] = 4.89), low energy (OR = 7.92), severe pain (OR = 14.92), multiple chronic conditions (OR = 2.71), and poor mental health (OR = 5.82), including moderate to severe anxiety (OR = 4.71) and depression (OR = 5.11).

CONCLUSION

Findings emphasize the unique sleep needs of Korean American older adults in senior housing and provide insights to improve their well-being. The study also highlights the need for further research using longitudinal designs, broader samples, and comprehensive sleep measures. [Journal of Gerontological Nursing, xx(x), xx-xx.].

Exploring Dapagliflozin's Influence on Autophagic Flux in Mania-like Behaviour: Insights from the LKB1/AMPK/LC3 Pathway in a Mouse Model

Mania-like episodes are neuropsychiatric disturbances associated with bipolar disorder (BD). Autophagic flux disturbance evolved as one of the molecular mechanisms implicated in mania. Recently, Dapagliflozin (DAPA) has corrected autophagic signaling in several neurological disorders. Yet, no endeavours examined the autophagic impact of DAPA in mania-like behaviours. This study aimed to investigate the effect of DAPA on disrupted autophagic pathways in a mouse model of mania-like behaviour. Mania-like behaviour was induced through paradoxical sleep deprivation (PSD) using the multiple-platform method for a duration of 36 h. Mice were divided into three groups, with DAPA (1 mg/kg/day, orally) administered for one week. Behavioural assessments were conducted on the 7th day. DAPA mitigated anxiety-like behaviour in the open field test and improved motor coordination and muscle tone in the rotarod test. Mechanistically, DAPA activated hippocampal autophagy-related markers; liver kinase B1/AMP-activated protein kinase (LKB1/AMPK) pathway, autophagy related gene 7 (ATG7), and microtubule-associated protein light chain 3II (LC3II). This was associated with reduced levels of the autophagosome receptor p62 protein, which subsequently enhanced GABAA receptor-associated protein (GABARAP), facilitating the surface presentation of GABAA receptors. Additionally, DAPA upregulated the GABAB receptor R2 subunit through trophic factors such as brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF). Furthermore, DAPA mitigated elevated serum stress hormones and restored the balance between proinflammatory and anti-inflammatory cytokines in both cortical and hippocampal tissues. These findings highlight the role of autophagic flux modulation by DAPA and its therapeutic potential in mitigating mania-like behaviours.

Exploring the nexus: Sleep disorders, circadian dysregulation, and Alzheimer's disease

We reviewed the connections among Alzheimer's disease (AD), sleep deprivation, and circadian rhythm disorders. Evidence is mounting that disrupted sleep and abnormal circadian rhythms are not merely symptoms of AD, but are also involved in accelerating the disease. Amyloid-beta (Aβ) accumulates, a feature of AD, and worsens with sleep deprivation because glymphatic withdrawal is required to clear toxic proteins from the brain. In addition, disturbances in circadian rhythm can contribute to the induction of neuroinflammation and oxidative stress, thereby accelerating neurodegenerative processes. While these interactions are bidirectional, Alzheimer's pathology further disrupts sleep and circadian function in a vicious cycle that worsens cognitive decline, which is emphasized in the review. The evidence that targeting sleep and circadian mechanisms may serve as therapeutic strategies for AD was strengthened by this study through the analysis of the molecular and physiological pathways. Further work on this nexus could help unravel the neurobiological mechanisms common to the onset of Alzheimer's and disrupted sleep and circadian regulation, which could result in earlier intervention to slow or prevent the onset of the disease.

Do Patients Sleep Better at Home or in the Hospital Following Primary Total Joint Arthroplasty?

INTRODUCTION

Despite increasing primary total joint arthroplasty [TJA] (total knee [TKA] and hip arthroplasty [THA]) rates in the United States, research on its impact on sleep quality is limited. The potential benefits of same-day discharge (SDD) post-TJA on sleep quality remain unexplored. This study examined whether patients undergoing SDD or overnight hospitalization experienced better sleep on the first night after surgery.

METHODS

In this prospective cohort study, patients undergoing THA or TKA were stratified by discharge status: SDD or overnight. The first postoperative night's sleep was assessed using the Richards-Campbell Sleep Questionnaire (RCSQ), the Insomnia Severity Index (ISI), and Fitbit-derived total sleep time (TST). Group differences were evaluated using analyses of covariance (ANCOVA) adjusted for age, sex, body mass index (BMI), Charlson Comorbidity Index (CCI), anesthesia type, and baseline ISI.

RESULTS

For THA, SDD was associated with higher RCSQ scores across several domains, including Total Score (d = 0.84, P = 0.0058), Sleep Depth (d = 0.82, P = 0.005), and Noise Disturbance (d = 1.22, P < 0.0001). Postoperative ISI was lower in SDD patients (d = 0.62, P = 0.010), and TST was longer (d = 1.03, P = 0.010). Higher postoperative ISI scores were strongly correlated with lower RCSQ and TST values. For TKA, SDD patients reported modest improvements in Sleep Depth (d = 0.59, P = 0.04) and Noise Disturbance (d = 0.97, P = 0.012), but no differences in total RCSQ, ISI, or TST (all P-values > 0.05). Associations between ISI, RCSQ, and TST were weak.

CONCLUSION

An SDD was associated with better early postoperative sleep after THA, including higher perceived quality and longer duration. While sleep benefits after TKA were more domain-specific, reductions in environmental disturbances suggest meaningful improvements in select aspects of rest. These findings support sleep as a modifiable perioperative outcome and support incorporating sleep quality into discharge planning.

Sleep Parameters and Quality of Life in Children with Monosymptomatic Nocturnal Enuresis: Association, Prediction and Moderation Analysis

Although often considered benign, monosymptomatic nocturnal enuresis (MNE) can significantly affect various domains of children's quality of life. This study aimed to investigate the relationship between polysomnography-derived sleep parameters and quality of life in children with MNE. Forty-four participants aged 8-12 years, with a diagnosis of MNE, underwent polysomnography and completed a quality of life questionnaire (PedsQL). Multiple linear regressions were used to assess the role of sleep variables in predicting four PedsQL domains. Moderation analysis was also performed to evaluate whether the N2 sleep percentage influenced the relationship between arousals and PedsQL. A higher frequency of microarousals predicted lower scores in the physical (B = -3.28, p = 0.01) and social (B = -3.50, p = 0.004) domains. A higher N2 sleep percentage was associated with better social (B = 0.69, p = 0.03) and school functioning (B = 0.88, p = 0.03). Moderation analysis revealed that N2 sleep amplified the negative impact of arousals on the social domain, particularly when the N2 sleep percentage was one standard deviation above the mean (B = -4.31, p < 0.001). The findings underscore the importance of sleep continuity and N2 stability for the quality of life of children with MNE. These results demonstrate the complex interaction between sleep and quality of life in pediatric enuresis.

Rest-activity rhythm fragmentation and synchronization are linked with reduced cortical thickness in older adults "at risk" for dementia

STUDY OBJECTIVES

While alterations in rest-activity rhythms are common in older adults "at risk" for dementia, it is unclear how rest-activity rhythms relate to underlying brain integrity.

METHODS

Older adults aged ≥50 years (n = 143, mean age = 67) with subjective and/or objective cognitive impairment underwent magnetic resonance imaging scanning and 14 days of actigraphy. The following nonparametric measures were computed: intra-daily variability (IV), inter-daily stability (IS), relative amplitude (RA), and average activity during the least active 5-h period (L5). A vertex-wise analysis correcting for age, sex, and clinical variables examined the association between nonparametric actigraphy measures and cortical thickness.

RESULTS

When controlling for age, sex, and body mass index (BMI), lower IV was associated with greater cortical thickness in the right cuneus (cluster-wise p-values [CWP] < 0.001), left middle frontal gyrus (CWP < 0.001), and lateral orbital frontal cortex (CWP = 0.004). When controlling for age, sex, medical burden (CIRS-G), BMI, and antidepressant use, lower IS was associated with lower cortical thickness in the left (CWP = 0.002) and right superior frontal gyrus (CWP < 0.001), left superior temporal gyrus (CWP = 0.043), and left post-central gyrus (CWP = 0.033). There were no significant associations between RA or L5 and cortical thickness.

CONCLUSIONS

In older adults "at risk" for dementia, variability and stability of rest-activity rhythms were associated with reduced cortical thickness in frontal, temporal, parietal, and occipital regions. Further studies could focus on determining the prognostic utility of such markers longitudinally.

Partial normalization of hippocampal oscillatory activity during sleep in TgF344-AD rats coincides with increased cholinergic synapses at early-plaque stage of Alzheimer's disease

Sleep alterations are known to occur in Alzheimer's disease (AD), before cognitive symptoms become apparent, and are thought to play an important role in the pathophysiology of AD. However, knowledge on the extent of macro- and microstructural changes of sleep during early, presymptomatic stages of AD is limited. We hypothesize that Aβ-induced perturbations of neuronal activity disrupt this oscillatory activity during sleep at pre-plaque stages of AD. In this study, we aimed to assess hippocampal oscillatory activity during sleep at pre- and early-plaque stages of AD, by performing 24-hour hippocampal electrophysiological measurements in TgF344-AD rats and wildtype littermates at pre- and early-plaque stages of AD. To provide a mechanistic understanding, histological analysis was performed to quantify GABA-ergic, glutamatergic and cholinergic synapses. We observed a differential impact of AD on hippocampal activity during rapid eye movement (REM) and non-REM (NREM) sleep, in the absence of robust changes in circadian rhythm. TgF344-AD rats demonstrated increased duration of sharp wave-ripples during NREM sleep, irrespective of age. Interestingly, a significantly decreased theta-gamma coupling was observed in TgF344-AD rats, prior to amyloid plaque deposition, which was partially restored at the early-plaque stage. The partial recovery of hippocampal activity during REM sleep coincided with an increased number of cholinergic synapses in the hippocampus during the early-plaque stage in TgF344-AD rats, suggestive of basal forebrain cholinergic compensation mechanisms. The results from this study reveal early changes in hippocampal activity prior to Aβ plaque deposition in AD. In addition, the current findings imply an important role of the cholinergic system to compensate for AD-related network alterations, thereby partially restoring sleep architecture and hippocampal activity.

Oxidative stress and inflammation mediate the association between Life's Crucial 9 and biological ageing: A secondary analysis of two observational studies

BACKGROUND

Life's Essential 8 (LE8) is known to have a negative correlation with biological aging, while the relationship between the Life's Crucial 9 (LC9) score, which includes mental health, and biological aging remains to be further investigated.

METHODS

We obtained data from two national cohorts, the UK Biobank and National Health and Nutrition Examination Survey (NHANES), to analyze the association between LC9 and biological aging. Biological aging was assessed using PhenoAge and KDMAge, with gender, race, and other indicators included as covariates. We applied linear regression models and restricted cubic splines (RCS) to analyze and describe the relationship. Furthermore, we explored the mediating role of oxidative stress and inflammation in the association between LC9 and biological aging. Subgroup analyses were conducted using multiple linear regression models, and differences between subgroups were assessed through interaction p-value tests. Sensitivity analyses were subsequently performed, followed by an exploration of the underlying mechanisms.

RESULTS

In this study, the UK Biobank cohort included 46,599 participants, with 44,973 participants having complete data for all covariates, LC9, and the necessary calculations for PhenoAge and KDMage. In the NHANES cohort, these numbers were 11,726 and 5,936, respectively. In the UK Biobank cohort, a significant association was found between the LC9 score and PhenoAge (β = -2.484, p < 0.001), with similar results observed for KDMage (β = -7.987, p < 0.001). Similar findings were observed in the NHANES cohort, with significant associations between the LC9 score and both PhenoAge (β = -5.327, p < 0.001) and KDMAge (β = 11.826, p < 0.001). These findings align with previous research suggesting that higher LC9 scores are associated with slower biological aging. After multivariable adjustment, an "inverse L-shaped" relationship was observed (non-linear P < 0.001). In the mediation analysis, oxidative stress and inflammation showed significant mediating effects between LC9 and both PhenoAge and KDMage (p < 0.001 for both). In the subgroup analysis, the LC9 score showed broad applicability, particularly among male participants aged over 60 years.

CONCLUSION

This cohort study suggests that higher LC9 scores are associated with slower biological aging. In addition to emphasizing diet and lifestyle habits, the role of mental health in biological aging should not be overlooked.

Slow wave synchrony during NREM sleep tracks cognitive impairment in prodromal Alzheimer's disease

INTRODUCTION

Alzheimer's disease (AD) disrupts human sleep architecture more severely than normal aging. However, it remains unclear how AD changes oscillatory neural activity during sleep, and whether such changes foreshadow cognitive decline in AD.

METHODS

We used high-density electroencephalography sleep recordings in 55 participants: (1) 21 healthy older adults, (2) 28 patients with amnestic mild cognitive impairment (aMCI)-a prodromal AD stage, and (3) 6 AD patients.

RESULTS

Cognitive performance robustly decreases with the slow wave (SW) trough amplitude and its synchronization across broad frontocentral cortical areas. Thus, across the AD spectrum, slow wave synchrony declines with cognition, as in normal aging, but at an accelerated pace. Moreover, delayed rapid eye movement (REM) sleep onset in aMCI and AD patients was associated with deficient SW activity, suggesting insufficiently restorative non-REM sleep.

DISCUSSION

These findings suggest that impaired slow waves are closely linked to cognitive impairment and mark disrupted neural activity in AD progression.

HIGHLIGHTS

Detailed analysis of high-density sleep electroencephalography was performed in amnestic mild cognitive impairment and Alzheimer's disease (AD) patients. Cognitive status robustly correlates with slow wave trough and its cortical spread. Delayed rapid eye movement sleep onset associated with AD correlates with diminished slow wave troughs. Impaired slow waves mark progressively disrupted neural activity in prodromal AD.

Effects of sleep on the glymphatic functioning and multimodal human brain network affecting memory in older adults

Understanding how sleep affects the glymphatic system and human brain networks is crucial for elucidating the neurophysiological mechanism underpinning aging-related memory declines. We analyzed a multimodal dataset collected through magnetic resonance imaging (MRI) and polysomnographic recording from 72 older adults. A proxy of the glymphatic functioning was obtained from the Diffusion Tensor Image Analysis along the Perivascular Space (DTI-ALPS) index. Structural and functional brain networks were constructed based on MRI data, and coupling between the two networks (SC-FC coupling) was also calculated. Correlation analyses revealed that DTI-ALPS was negatively correlated with sleep quality measures [e.g., Pittsburgh Sleep Quality Index (PSQI) and apnea-hypopnea index]. Regarding human brain networks, DTI-ALPS was associated with the strength of both functional connectivity (FC) and structural connectivity (SC) involving regions such as the middle temporal gyrus and parahippocampal gyrus, as well as with the SC-FC coupling of rich-club connections. Furthermore, we found that DTI-ALPS positively mediated the association between sleep quality and rich-club SC-FC coupling. The rich-club SC-FC coupling further mediated the association between DTI-ALPS and memory function in good sleepers but not in poor sleepers. The results suggest a disrupted glymphatic-brain relationship in poor sleepers, which underlies memory decline. Our findings add important evidence that sleep quality affects cognitive health through the underlying neural relationships and the interplay between the glymphatic system and multimodal brain networks.

Age-related disturbances in rest-activity rhythms and integrity of the hippocampal network: An exploratory study

To better understand the relationship between the rest-activity rhythms and cognitive impairments during aging, we assessed the longitudinal changes in the rest-activity rhythms in an elderly population and their possible detrimental effect on the hippocampal network. This was done longitudinally in a rural cohort with two actigraphic assessments and brain imaging examinations, seven years apart. A segmentation of the hippocampus and its related structures was used to assess volumes and functional connectivity in this network based on anatomical and resting state functional data. Regression models were carried out to investigate the potential association of the evolution of sleep and rest-activity rhythms parameters with the structural and functional integrity of the hippocampal network. Our sample was composed of 33 subjects aged 75.2 ± 2.4 years old at the first time point with 40% of women. After seven years, the sleep of our participants did not change but their rest-activity rhythms did (p < 0.05), with a decrease in relative amplitude (∂RA = -0.021) and stability (∂IS = -0.044) as well as an increase in fragmentation (∂IV = +0.072). The deterioration of rest-activity rhythms was correlated with a lower anterior hippocampal volume (p corrected <0.05) while no correlation with functional connectivity was observed. These findings suggest that a degradation of rest-activity rhythms in people over 70 years old could constitute a factor of hippocampal vulnerability. Preventive interventions should consider rest-activity rhythms in the oldest-old population.

Towards proactively improving sleep: machine learning and wearable device data forecast sleep efficiency 4-8 hours before sleep onset

Wearable devices with sleep tracking functionalities can prompt behavioral changes to promote sleep, but proactively preventing poor sleep when it is likely to occur remains a challenge due to a lack of prediction models that can forecast sleep parameters prior to sleep onset. We developed models that forecast low sleep efficiency 4 and 8 hours prior to sleep onset using gradient boosting (CatBoost) and deep learning (Convolutional Neural Network Long Short-Term Memory, CNN-LSTM) algorithms trained exclusively on accelerometer data from 80,811 adults in the UK Biobank. Associations of various sleep and activity parameters with sleep efficiency were further examined. During repeated cross-validation, both CatBoost and CNN-LSTM exhibited excellent predictive performance (median AUCs > 0.90, median AUPRCs > 0.79). U-shaped relationships were observed between total activity within 4 and 8 hours of sleep onset and low sleep efficiency. Functional data analyses revealed higher activity 6 to 8 hours prior to sleep onset had negligible associations with sleep efficiency. Higher activity 4 to 6 hours prior had moderate beneficial associations, while higher activity within 4 hours had detrimental associations. Additional analyses showed that increased variability in sleep duration, efficiency, onset timing, and offset timing over the preceding four days was associated with lower sleep efficiency. Our study represents a first step towards wearable-based machine learning systems that proactively prevent poor sleep by demonstrating that sleep efficiency can be accurately forecasted prior to bedtime and by identifying pre-bed activity targets for subsequent intervention.

Self-report and actigraphy measures of sleep and domain-specific cognitive performance in older adults

Poor sleep is associated with worse cognitive function in older adults. However, nuanced associations between sleep and cognition might be masked by the multidimensional nature of sleep which requires multiple approaches (e.g., self-report and actigraphy) to gain meaningful insight. We investigated associations of sleep with cognition and hypothesized that the most consistent association would be between self-reported sleep duration and actigraphy-measured wake after sleep onset (WASO). We utilized baseline data from the Investigating Gains in Neurocognition in an Intervention Trial of Exercise study. Cognitively unimpaired older adults (n=589, aged 65-80) completed a comprehensive cognitive assessment with generation of five domain-specific cognitive composite scores. Sleep was measured via the Pittsburgh Sleep Quality Index (PSQI) and 24-h actigraphy (GT9X Link). Greater actigraphy WASO and shorter self-reported sleep duration were associated with poorer performance in all five cognitive domains (β[range: WASO] = -0.14 to -0.19, all p<0.05; β[range: duration] = 0.08-0.15, all p<0.05). Shorter actigraphy sleep duration was also associated with poorer EF/attentional control (β=0.09, p=0.020) and processing speed (β=0.10, p=0.013). Actigraphy and self-reported sleep were more strongly associated with episodic memory in older (74 years) and younger (66 years) individuals, respectively. Actigraphy-derived WASO was consistently and robustly associated with cognitive performance. Additionally, our results suggest that self-reported sleep duration provides insight into sleep behaviors related to brain health (e.g., long periods of still wakefulness), beyond actigraphy-measured sleep duration. Thus, both self-report and actigraphy measures of sleep provide critical and unique information for interpreting relationships with cognitive performance.

Greenspace proximity in relation to sleep health among a racially and ethnically diverse cohort of US women

Sleep is essential for overall health. Greenspace may contribute to sleep health through, for instance, improving mood, reducing sleep disruptors (e.g., poor air quality), and promoting physical activity. Although greenspace likely differs across populations, few studies have included diverse populations. To investigate greenspace-sleep health associations, overall and by age, race and ethnicity, and socioeconomic status, we used data collected at enrollment (2003-2009) from women in the Sister Study (n = 1612 Hispanic/Latina, n = 4421 non-Hispanic (NH)-Black, and n = 41,657 NH-White). Participants' geocoded home addresses were linked to NASA's Moderate Resolution Imaging Spectroradiometer Normalized Difference Vegetation Index data (250m resolution) to capture greenspace tertiles (further categorized as low/moderate vs. high). Participants reported seven sleep dimensions, which we assessed individually, along with a multidimensional sleep health measure (categories: favorable, moderate, poor). Adjusting for individual- and environmental/neighborhood-level characteristics, we used Poisson regression with robust variance to estimate prevalence ratios and 95 % confidence intervals (PR[CI]). We tested for interaction and estimated age-, race and ethnicity-, and educational attainment category-specific associations. Among participants (mean ± SD age = 55.7 ± 9.0 years), those with low/moderate vs. high greenspace had a lower prevalence of favorable sleep (58 % vs. 66 %). After adjustment, low/moderate vs. high greenspace was associated with a 32 % higher prevalence of moderate (PR = 1.32 [1.27-1.38]) and 12 % higher prevalence of poor (PR = 1.12 [1.07-1.16]) vs. favorable sleep health. Magnitudes of associations were higher among NH-White women vs. minoritized racial-ethnic groups and women with higher vs. lower educational attainment. Higher greenspace was associated with favorable sleep, with stronger associations among groups with more social advantages.

Weekend catch-up sleep and frailty in US adults: a cross-sectional study from NHANES 2017-2020

BACKGROUND

Frailty is an age-related condition characterized by vulnerability to adverse health outcomes. Adequate sleep may reduce frailty risk, many individuals rely on weekend catch-up sleep (WCS) to offset weekday deficits. However, the relationship between WCS and frailty remains poorly understood. This study aims to clarify the association between WCS and frailty.

METHODS

We conducted secondary data analyses using data from 7714 adult participants in the National Health and Nutrition Examination Survey (NHANES 2017-2020). Sleep duration was assessed through self-reported questions, while frailty was evaluated using the frailty index. WCS duration was then computed as the difference between weekend and weekday sleep durations, with WCS defined as WCS duration ≤ 0 h, 0-2 h, or ≥ 2 h. A frailty index of 0.25 or greater is considered frailty. Multivariate logistic regression analyses were conducted to explore the association between WCS and frailty.

RESULTS

In fully adjusted models, participants with 0-2 h of WCS had significantly lower odds of frailty (OR 0.709; 95% CI, 0.518-0.969; P = 0.035) compared to those with no WCS (≤ 0 h). However, the association was not significant for those with ≥ 2 h of WCS (OR 0.812; 95% CI, 0.550-1.200; P = 0.248). Subgroup analyses indicated no significant interaction across subgroups (P for interaction > 0.05).

LIMITATIONS

The cross-sectional design limits our ability to infer causality, and the reliance on self-reported sleep data may introduce measurement bias. Additionally, the frailty index, while validated, may not capture all dimensions of frailty. Future longitudinal studies with objective sleep measurements are needed to confirm these findings.

CONCLUSIONS

Our findings suggest that moderate WCS (0-2 h) may be associated with a lower prevalence of frailty, although the relationship is not linear and requires further investigation. These findings contribute to the emerging evidence base linking sleep patterns with frailty risk, warranting further prospective investigation.

Five-Year Changes in 24-Hour Sleep-Wake Activity and Dementia Risk in Oldest Old Women

BACKGROUND AND OBJECTIVES

Sleep disruptions are associated with cognitive aging in older adults. However, little is known about longitudinal sleep changes in the oldest old and whether these changes are linked to cognitive impairment. We aimed to determine whether changes in 24-hour multidimensional sleep-wake activity are associated with mild cognitive impairment (MCI) and dementia in oldest old women.

METHODS

We studied cognitively unimpaired women enrolled in the Study of Osteoporotic Fractures who completed wrist actigraphy twice (baseline and follow-up) and had cognitive status evaluated at follow-up using a neuropsychological battery and adjudication. To identify multidimensional sleep-wake change profiles, we performed hierarchical clustering on principal components on the 5-year changes (median 5.0 [range 3.5-6.3] years) in nighttime sleep (sleep duration, sleep efficiency [SE], and wake after sleep onset [WASO]), napping (duration and frequency), and circadian rest-activity rhythms (RARs; acrophase, amplitude, mesor, and robustness). Using multinomial logistic regression, we evaluated the associations between these profiles-and individual parameter changes-and MCI and dementia risk at follow-up.

RESULTS

Of 733 participants (mean age 82.5 ± 2.9 years), 164 (22.4%) developed MCI and 93 (12.7%) developed dementia by the follow-up visit. We identified 3 sleep-wake change profiles: stable sleep (SS; n = 321 [43.8%]) was characterized by stability or small improvements; declining nighttime sleep (n = 256 [34.9%]) showed decreases in nighttime sleep quality and duration, moderate napping increases, and worsening circadian RARs; and increasing sleepiness (IS; n = 156 [21.3%]) exhibited large increases in daytime and nighttime sleep duration and quality, and worsening circadian RARs. After adjustment for age, education, race, body mass index, diabetes, hypertension, myocardial infarction, antidepressant use, and baseline cognition, women with IS had approximately double the risk of dementia (odds ratio 2.21, 95% CI 1.14-4.26) compared with those with SS. SE, WASO, nap duration, and nap frequency were individually associated with dementia. Neither sleep-wake change profiles nor individual parameters were associated with MCI.

DISCUSSION

Among community-dwelling women in their 80s, those with increasing 24-hour sleepiness over 5 years had doubled dementia risk during that time. Change in multidimensional 24-hour sleep-wake activity may serve as an early marker or risk factor for dementia in oldest old women.

Influence of sleep and cardiovascular health on cognitive trajectories in older adults

Age-related changes in sleep have been associated with cognitive decline, yet causal pathways have not been identified. Evidence suggests reduced cardiovascular health may be a consequence of poor sleep and a precursor to cognitive decline. This observational cohort study used path analyses to determine whether cardiovascular disease risk mediated or moderated effects of sleep on yearly longitudinal change in cognition, estimated with linear growth models. Total sleep time (TST), sleep efficiency (SE), and relative spectral power of slow wave activity (SWA; 1-4 Hz) and slow oscillations (SO; 0.5-1 Hz), were measured with single-channel home EEG. Cardiovascular disease risk (CVR) was estimated as 10-year Framingham Risk Score 1-year post-sleep. Outcomes were yearly change in executive function (EF), episodic memory (EM), and processing speed (PS) over 2-5 years post-sleep. 342 participants (mean age 73.5 +/- 5.6 years, 51 % female) were included. Shorter TST was linearly associated with increased CVR across all models (βs = -0.18(0.058) - -0.19(0.059), ps< 0.002). TST was indirectly associated with EF and PS decline through CVR, such that associations between short TST and cognitive decline were partially due to higher CVR. All other mediating and moderating effects were nonsignificant after multiple comparisons. Indirect associations between short sleep duration and greater decline in executive function and processing speed were found through higher CVR, suggesting a potential mechanism by which sleep leads to cognitive decline. Findings support the prioritization of adequate sleep duration to preserve both cardiovascular and cognitive health in later life.

Sleep quality of college students in Fujian and its influencing factors: A cross-sectional study

AIM

This study aims to investigate college students' sleep quality, explore the factors influencing it, and provide data support for further studies.

METHODS

College students in Fujian Province were chosen as the study sample using snowball sampling. Data was gathered from the participants through the utilization of a self-designed personal questionnaire, the Pittsburgh Sleep Quality Index(PSQI) scale, and the Mobile Phone Addiction Index (MPAI) scale. Binary logistic regression is utilized to assess the sleep quality of college students and identify risk factors.

RESULTS

A total of 971 participants were included in this study. The mean total PSQI score was 4.52 ± 3.17. There were 310 students with poor sleep quality and the detection rate was 32.0%. The multivariate logistic regression analysis showed that smoking (OR(Odds ratio):1.832(1.076,3.118)), electronic product addiction(OR:2.861(1.928,4.246)), personal history of acute illness(OR:2.328(1.671,3.244)) were identified as independent risk factors.In turn, education (OR:0.594(0.456,0,772)) and parents without sleep problems (OR:0.533(0.361,0.787)) were protective factors.

CONCLUSION

College students in Fujian have some sleep problems. We should pay attention to the relationship between smoking, electronic product addiction, personal history of acute illness and sleep quality. Health policymakers should consider these factors to improve college students' sleep quality.

Association Between Internet Use and Sleep Health Among Middle-Aged and Older Chinese Individuals: Nationwide Longitudinal Study

BACKGROUND

Sleep disorders are common among older adults and have a bidirectional impact on their emotional well-being. While some studies suggest that internet use may offer mental health benefits to this population, the relationship between internet use and sleep outcomes remains underexplored.

OBJECTIVE

This study investigates the association between internet use (including use frequency) and sleep quality and duration in middle-aged and older Chinese adults.

METHODS

A longitudinal analysis was conducted using the China Health and Retirement Longitudinal Study data from 2015 to 2018. Sleep quality was assessed using the sleep item from the Centre for Epidemiologic Studies Depression Scale, categorized as "good" (<1 day; reference), "fair" (1-4 days), or "poor" (5-7 days). Sleep duration was classified as short (<6 hours), medium (6-9 hours; reference), or long (>9 hours). Adjusted multinomial logistic regressions were used to examine the associations between internet use or frequency in 2015 and sleep quality or duration in 2018, controlling for age, sex, residence, diseases, smoking, drinking, and napping time and further exploring sex and age group variations.

RESULTS

The baseline analysis included 18,460 participants aged 45 years and older, with 1272 (6.9%) internet users, 8825 (48.1%) participants had fair or poor sleep, and 6750 (37.2%) participants had abnormal sleep duration. Internet users, particularly those who used it almost daily, were less likely to report poor sleep quality (relative risk [RR] 0.71, 95% CI 0.54-0.94) and longer sleep duration (RR 0.22, 95% CI 0.11-0.44) than nonusers. In the longitudinal analysis, baseline internet users had a significantly reduced risk of fair (RR 0.66, 95% CI 0.51-0.86) and poor sleep quality (RR 0.60, 95% CI 0.44-0.81), as well as short (RR 0.73, 95% CI 0.53-1.00) and long sleep duration (RR 0.39, 95% CI 0.21-0.72) during the follow-up period than nonusers. These associations remained significant for almost daily internet use (RR 0.32, 95% CI 0.15-0.69). Subgroup analyses by sex revealed a positive relationship between internet use and sleep quality, with a stronger effect in female (poor sleep: RR 0.57, 95% CI 0.36-0.89) than male (poor sleep: RR 0.61, 95% CI 0.40-0.92) participants. The effect on sleep duration was significant only in daily male users, showing a reduced risk of long sleep duration (RR 0.30, 95% CI 0.11-0.78). In the age subgroup analysis, most internet users were in the 45- to 59-year age group, with results consistent with the overall findings.

CONCLUSIONS

This study suggests that internet use is associated with a reduced risk of sleep problems in middle-aged and older adults. The findings indicate that moderate, regular internet engagement-such as daily use-may promote better sleep health in this population.

Multi-task exercise increases delta power in non-rapid eye movement sleep among older female adults: A randomized crossover trial

Delta power in electroencephalography during sleep has been used as a more quantitative approach to determine sleep depth and quality. Despite the positive effects of both exercise and cognitive activity on delta power during sleep, limited information is available regarding the effects of multi-task exercise, which combines these two activities. Therefore, this study aimed to investigate the impact of multi-task exercise on delta power during sleep. Fifteen older female adults participated in both multi-task and single-task exercises at low and moderate-to-vigorous intensities for 30 min each. Sleep architecture was recorded using polysomnography to compare the amount of delta power during sleep. Additionally, cortical hemodynamic changes in the prefrontal cortex were monitored using functional near-infrared spectroscopy before and after each exercise session. Low-intensity multi-task exercise increased cortical activation in the right and left ventrolateral prefrontal cortex and frontopolar area, which positively correlated with the increase in delta power. This study provides the first experimental evidence that low-intensity multi-task exercise enhances cortical activation in the prefrontal cortex of older female adults, leading to an increase in delta power during sleep. It also suggests that low-intensity multi-task exercise may be a more useful intervention for improving sleep quality in older adults.

Slow-wave sleep is associated with nucleus accumbens volume in elderly adults

Slow-wave sleep (SWS) is essential for restorative neural processes and its decline is associated with both healthy and pathological ageing. Building on previous rodent research, this longitudinal study identified a significant association between nucleus accumbens (NAcc) volume and SWS duration in cognitively unimpaired older adults, whilst no significant link was observed between NAcc volume and N2 or rapid eye movement (REM) sleep percentage. Our findings support the involvement of the NAcc in ageing-related modulation of SWS and thus suggest the NAcc as a potential neural marker or therapeutic target for improving SWS.

Melatonin and the nervous system: nanomedicine perspectives

The mechanism of action of melatonin on the nervous system, sleep, cognitive deficits, and aging is not fully understood. Neurodegenerative diseases (ND) are one of the leading causes of disability and mortality worldwide. Sleeping and cognitive impairments also represent common and serious public health problems, particularly deteriorating with the aging process. Melatonin, as a neuromodulatory hormone, regulates circadian rhythms and the sleep-wake cycle, with functions extending to antioxidant, anti-inflammatory, neuroprotective, and anti-aging properties. However, melatonin is a hydrophobic compound with relatively low water solubility and a short half-life. While melatonin can cross the blood-brain barrier, exogenous melatonin administered orally or intravenously has poor bioavailability, undergoes rapid metabolism in the circulation, and shows limited brain accumulation, ultimately compromising its therapeutic efficacy. In recent years, the convergence of melatonin research with nanomedicine ensures safe therapeutic uses, limited drug degradation, and perspectives for targeted drug delivery to the central nervous system. Here we outline the promising neurotherapeutic properties of nanomaterials as carriers loaded with melatonin drug alone or in combinations with other active molecules.

Associations between plasma proteomic signatures and secondary sleep in older adults

Sleep disturbances are prevalent among elderly populations and are linked to various health complications. Understanding the underlying biological mechanisms contributing to sleep disorders is crucial for developing targeted interventions. In this study, we measured 355 plasma proteins in an elderly Japanese cohort (n=77) using a high-throughput proteomic platform. Additionally, we collected over 25,000 person-days of physical activity and sleep behavior data from wrist-worn wearable devices, focusing on total sleep time (TST) across 24 h and daytime sleep. Fragmented sleep was observed as one of the most prevalent sleep disturbances in this population. In protein expression analysis, we identified 9 protein biomarkers associated with increased secondary sleep TST, defined as additional sleep episodes outside of the main sleep episode within 24 h. These findings may suggest disruptions in circadian rhythms or underlying health conditions. Functional analysis revealed that biological processes related to inflammation play a significant role in regulating sleep behavior. Further analysis showed an association of 12 proteins with daytime sleep and 5 proteins with afternoon sleep. Overall, this study identified inflammatory biomarkers and biological processes associated with sleep behavior in the elderly, presenting promising opportunities for developing diagnostic tools and targeted clinical interventions.

Sleep Alterations and Cognitive Decline

Sleep disturbances and cognitive decline are intricately connected, and both are prevalent in aging populations and individuals with neurodegenerative disorders such as Alzheimer's disease (AD) and other dementias. Sleep is vital for cognitive functions including memory consolidation, executive function, and attention. Disruption in these processes is associated with cognitive decline, although causal evidence is mixed. This review delves into the bidirectional relationship between alterations in sleep and cognitive impairment, exploring key mechanisms such as amyloid-β accumulation, tau pathology, synaptic homeostasis, neurotransmitter dysregulation, oxidative stress, and vascular contributions. Evidence from both experimental research and population-based studies underscores the necessity of early interventions targeting sleep to mitigate risks of neurodegenerative diseases. A deeper understanding of the interplay between sleep and cognitive health may pave the way for innovative strategies to prevent or reduce cognitive decline through improved sleep management.

Impact of spindle-inspired transcranial alternating current stimulation during a nap on sleep-dependent motor memory consolidation in healthy older adults

With the increase in life expectancy and the rapid evolution of daily life technologies, older adults must constantly learn new skills to adapt to society. Sleep reinforces skills acquired during the day and is associated with the occurrence of specific oscillations such as spindles. However, with age, spindles deteriorate and thus likely contribute to memory impairments observed in older adults. The application of electric currents by means of transcranial alternating current stimulation (tACS) with spindle-like waveform, applied during the night, was found to enhance spindles and motor memory consolidation in young adults. Here, we tested whether tACS bursts inspired by spindles applied during daytime naps may (i) increase spindle density and (ii) foster motor memory consolidation in older adults. Twenty-six healthy older participants performed a force modulation task at 10:00, were retested at 16:30, and the day after the initial training. They had 90-minute opportunity to take a nap while verum or placebo spindle-inspired tACS bursts were applied with similar temporal parameters to those observed in young adults and independently of natural spindles, which are reduced in the elderly. We show that the density of natural spindles correlates with the magnitude of memory consolidation, thus confirming that spindles are promising physiological targets for enhancing memory consolidation in older adults. However, spindle-inspired tACS, as used in the present study, did not enhance either spindles or memory consolidation. We therefore suggest that applying tACS time-locked to natural spindles might be required to entrain them and improve their related functions.

Effect of androgen receptor blockade on spatial memory in young and aged male rats in the Barnes maze

Spatial memory declines with age, and this decline is associated with decreased testosterone levels. However, the specific role of the androgen receptor in spatial memory performance in both young and aged rats remains largely unexplored. Our study aimed to investigate the effects of chronic androgen receptor blockade on spatial memory performance in young and aged male rats. Young (3 months old) and aged (21 months old) Wistar rats were assigned to one of three experimental groups: control, vehicle-, or flutamide-treated (10 mg/kg SC for 14 days). Spatial memory was evaluated using the Barnes maze (Days 8-14 of flutamide administration). The phases of spatial memory acquisition (4 daily trials/4 days) and retention (1 trial/day, 3 days after acquisition) were evaluated. The results indicated that older animals took longer to find the goal, traveled greater distances, and moved more slowly than their younger counterparts in the Barnes maze, regardless of treatment. During the acquisition phase, flutamide administration delayed learning in both young and aged animals. Specifically, flutamide-treated animals exhibited delayed learning during the assessment of overnight forgetting (trial 1 on each day of the acquisition phase). During the retention phase, an age-related effect was observed in the flutamide-treated groups. These findings suggest that androgen receptor blockade induces cognitive deficits in both young and aged male rats, supporting the modulatory role of endogenous androgens in memory function.

The yin and yang of sleep-wake regulation: gender gap in need for sleep persists across the human lifespan

PURPOSE

Experiments on sleep regulation under the condition of self-selected light-dark and wake-sleep cycle revealed a larger sleep fraction in women than men. In questionnaire studies, women usually report a greater need for sleep than men. They also sleep more than men in overall and at most life course stages. However, much of the gap was explained by work/family responsibilities and gendered time tradeoffs. We tested whether females from childhood to late adulthood spend longer time in bed than males on weekends, and whether on weekdays, their time in bed fails to become longer due to the socially rather than biologically governed earlier weekday wake ups.

METHODS

A set of 340 paired subsamples of male and female sleep times was analyzed. The averaged sleep times were calculated and simulated.

RESULTS

Female-male difference in weekend time in bed attained the value of 0.26 h (the 0.16-h earlier bedtime was combined with the 0.10-h later risetime). The gender gap in weekday risetime was non-significant and the direction of gender difference in weekday time in bed was inconsistent across the lifespan. Model-based simulations provided support for the prediction that the male-female gap in sleep desire can reflect a higher level of sleep slow-wave activity (SWA) in females found in the vast majority of published studies.

CONCLUSION

Since SWA is strongly indicative of age and age-associated change in neuronal networks, the persistency of female's greater desire for sleep can be explained by the underlying sex difference in age-associated structural changes in these networks.

Self-compassion education for older adults' mental health and wellbeing: a mixed methods systematic review

OBJECTIVES

To assess and explore the influence of self-compassion education for older adults' mental health and wellbeing; and identify facilitators and challenges that may impact providing self-compassion education for older adults' mental health and wellbeing.

METHOD

A mixed methods systematic review was conducted following Joanna Briggs Institute (JBI) methodology. A three-stage search approach was undertaken that included six electronic databases: Medline, Embase, PsycINFO, Emcare, Ovid Nursing, Cochrane Library, and grey literature. Quality assessment was conducted via mixed methods appraisal tools. Quantitative data were synthesised into a narrative summary of the characteristics and findings of the influence of self-compassion education for older adults. For the qualitative data, a thematic synthesis was conducted.

RESULTS

Eleven studies met the inclusion criteria. Overall, the included studies reported that self-compassion education for older adults was associated with improved psychological well-being, and higher levels of self-compassion, kindness towards oneself and others, and mindfulness. In addition, participants reported reduced distress, anxiety, and avoidance of negative experiences.

CONCLUSION

The findings provide evidence to guide further research on developing, designing, facilitating, and evaluating self-compassion education programs and workshops for older adults.

PROSPERO REGISTRATION

This systematic review is registered at the International Prospective Register of Systematic Reviews: PROSPERO 2022 CRD42022310630.

Sleep Health and Psychological Wellbeing in Adult Women: A Specific Focus on Endometriosis-A Survey Study

Background: Endometriosis is a chronic, oestrogen-sensitive inflammatory disease, which can have a significant impact on women's wellbeing. Nevertheless, the sleep health of this population has been poorly investigated. This exploratory study aimed at describing sleep health, psychological wellbeing, and prevalence of endometriosis among a sample of female students and at evaluating the impact of endometriosis on sleep health and psychological wellbeing in women suffering from the disease. Methods: Women were recruited with a two-stage procedure in a cross-sectional study using online questionnaires: Insomnia Severity Index, Hospital Anxiety and Depression Scale, and Difficulties in Emotion Regulation Scale-Short form. Furthermore, specific questions were used to measure the five dimensions of sleep health: satisfaction, vigilance, efficiency, duration, and timing. Results: In the first stage of the enrolment procedure, 1068 students (18-45 years old) responded to the questionnaire, and 8.7% reported a physician diagnosis of endometriosis. Additionally, in the second stage of the enrolment procedure, 75 women were recruited through social media and reported a diagnosis of endometriosis. Then, all women with endometriosis (169) were age-matched with 169 women without the disease. Multivariate regression analyses showed a bidirectional association between sleep health and psychological wellbeing in the matched sample. Independent samples t-test showed that women with endometriosis reported more severe insomnia symptoms and lower psychological wellbeing than controls. Statistically significant differences were also found in global sleep health and satisfaction, vigilance, and efficiency. Among women with endometriosis, pain and anxiety symptoms were bidirectionally associated, while sleep health was significantly associated with disease stage and psychological difficulties. Conclusions: Considering and treating sleep difficulties in this population may contribute to an improvement in psychological wellbeing and quality of life.

The night's watch: Exploring how sleep protects against neurodegeneration

Sleep loss is often regarded as an early manifestation of neurodegenerative diseases given its common occurrence and link to cognitive dysfunction. However, the precise mechanisms by which sleep disturbances contribute to neurodegeneration are not fully understood, nor is it clear why some individuals are more susceptible to these effects than others. This review addresses critical unanswered questions in the field, including whether sleep disturbances precede or result from neurodegenerative diseases, the functional significance of sleep changes during the preclinical disease phase, and the potential role of sleep homeostasis as an adaptive mechanism enhancing resilience against cognitive decline and neurodegeneration.

Sleep and Aging. A Polysomnographic Follow-Up Study, Some 40 Years Later

The aim of the present study was to explore age-related sleep alterations in normal subjects whose sleep had been recorded for the first time 40.4 ± 4.8 years ago. For the follow-up polysomnography (3 nights) 15 participants (5 female, 10 male, age 56-74 years) were recruited. Recording conditions and sleep scoring were adapted to the previous study. In all older participants, the amount of slow-wave sleep and REM sleep was decreased, while stage 1 and wakefulness were increased. There was no significant change in stage 2 or in any of the additional REM sleep parameters (REM density, latency, number and duration of REM cycles). Sleep stage transition analysis showed a markedly reduced stability of SWS from young to older age. While none of the single sleep parameters showed intra-individual stability with age, a pattern analysis, which combined seven sleep parameters (sleep stages, total sleep time and REM density), showed that the concordance rate of the combined sleep parameters correlated significantly with the age at follow-up. The results of this longitudinal study over a period of about 40 years are largely consistent with those of cross-sectional studies. While the lack of significant correlation of the individual sleep parameters between the younger and older age groups did not allow for the identification of any of them as trait markers, the result of the pattern analysis, which combined a set of sleep parameters, indicates that the stability of the sleep structure decreases significantly in the age range between the late 50s and early 70s.

The effectiveness of exercise interventions in the improvement of sleep in older adult people: a meta-analysis

Background

Sleep problems are prevalent among the older adult population, with a significant impact on their health and overall well-being. Several randomized controlled trials (RCTs) have yielded controversial results regarding the efficacy of exercise interventions in the improvement of sleep among older adult people. This systematic review and meta-analysis aim to assess the influence of exercise interventions on sleep quality within this demographic.

Methods

A search was conducted across four databases, namely Web of Science, PubMed, Embase, and SportDiscus, in order to identify randomized controlled trials investigating exercise interventions and sleep in the older adult. The quality of the studies included was evaluated by two researchers according to the PEDro scale. Meta-analysis and sensitivity analysis were performed utilizing RevMan 5.4 and Stata 17 software.

Result

A total of fifty studies encompassing 3,937 participants were included in the analysis. Regarding patient-reported sleep parameters, exercise interventions exhibited enhancements in sleep quality (WMD = -2.18, 95%CI: -2.83 to -1.53, p < 0.01) and reductions in insomnia severity (SMD = -0.52, 95%CI: -0.79 to -0.25, p < 0.01), albeit without significant improvements in daytime sleepiness (SMD = -0.66, 95%CI: -1.41 to 0.09, p = 0.09). In terms of clinician-reported sleep parameters, exercise interventions resulted in increased total sleep time (WMD = 8.98, 95%CI: 1.19 to 16.78, p < 0.05) and sleep efficiency (WMD = 3.66, 95%CI: 2.46 to 4.85, p < 0.01), and reduced wake time after sleep onset (WMD = -11.85, 95%CI: -15.58 to -8.11, p < 0.01), but did not decrease sleep onset latency (WMD = -3.05, 95%CI: -6.23 to 0.13, p = 0.06) or the number of awakenings during sleep (WMD = -0.73, 95%CI: -1.98 to 0.52, p = 0.25).

Conclusion

Exercise interventions have demonstrated positive effects on enhancing sleep quality among the older adult population. This study lends support to the utilization of exercise interventions as a safe, feasible, and effective non-pharmacological treatment approach for enhancing sleep among older individuals.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/view/CRD42024530227, Identifier CRD42024530227.

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.

Effects of Sleep-Disordered Breathing on Daytime Brain Activity in Community-Dwelling Older Adults

Introduction  Sleep-disordered breathing (SDB) is associated with an increased risk of cardiovascular diseases. The present study aimed to examine the influence of SDB on daytime brain activity in the community-dwelling older adults. Material and Methods  Eighty one consecutive volunteers aged 60 years or older (mean age 70.5 ± 4.8 years) participated in the present study. Daytime brain activity was assessed by measuring the peak cortical oxygenated hemoglobin (OxyHb) levels and area under the near-infrared spectroscopy (NIRS) curve. The respiratory event index (REI) and 3% oxygen desaturation index (3%ODI) were evaluated using a home sleep-apnea test. Results  The peak OxyHb and area under the NIRS curve were significantly lower in the participants with REI ≥ 15/h than those with REI < 15/h. The body mass index (BMI), REI, 3%ODI, and Epworth sleepiness scale (ESS) scores were significantly correlated with peak OxyHb levels (BMI: r  = -0.202, p  = 0.035; REI: r  = -0.307, p  = 0.003; 3%ODI: r  = -0.321, p  = 0.002; and ESS score: r  = -0.287, p  = 0.005). Also, the BMI, REI, and 3%ODI were significantly correlated with the area under the NIRS curve (BMI: r  = -0.306, p  = 0.002; REI: r  = -0.326, p  = 0.002; and 3%ODI: r =-0.322, p  = 0.002), and BMI was a significant factor associated with the area under the NIRS curve. Conclusions  Brain activity during wakefulness was associated with severities of SDB and obesity. A simple NIRS may yield unique information for characterizing the decline in daytime brain activity of the community-dwelling older adults.

Emerging Technologies to Track and Improve Sleep Health

This review explores cutting-edge advancements, including wearable sleep trackers, brain age assessments, transcranial electrical stimulation (TES), acoustic stimulation, and glymphatic system modulation. Sleep trackers provide continuous monitoring of sleep patterns, while brain age estimation offers insights into brain health and early detection of accelerated aging. TES shows promise in improving mood, memory, and sleep. Acoustic stimulation during slow-wave sleep has been demonstrated to enhance memory consolidation. Additionally, optimizing the glymphatic system may facilitate brain waste clearance, crucial in preventing neurodegenerative diseases like Alzheimer's. However, significant challenges remain, including the need for rigorous longitudinal studies to validate these technologies' efficacy and safety.

Exploring the association between sleep problems and loneliness in adolescents: Potential mediating effects of rumination and resilience

Sleep problems positively predict loneliness to a large extent, which would harm adolescent health. However, little is known about the underlying mechanism. This research investigates the potential mediating roles of rumination and resilience in the relation among adolescents and further examines the changing relationships. In Study 1, 1056 adolescents from two schools completed self-reported measures of sleep problems, loneliness, rumination, and resilience. We found that sleep problems were positively associated with loneliness, and that rumination and resilience mediated this relationship, both individually and sequentially. To examine the varying relationship between rumination, resilience, and loneliness, Study 2 adopted the cross-lagged design in a long-term longitudinal study of 131 students and found that rumination and resilience at T1 significantly predict loneliness at T2. To further directly explore the changing relationship between sleep problems and loneliness, we performed a short-term longitudinal study across 7 weeks of 242 adolescents in Study 3. The results replicated the findings of Study 2 and found sleep problems at T1 positively predicted loneliness at T2. These results underscore the significance of sleep problems in contributing to loneliness through mediating mechanisms and unveil the possible causal relationships, offering robust insights to alleviate adolescent loneliness.

The aging human brain exhibits reduced cerebrospinal fluid flow during sleep due to both neural and vascular factors

Aging reduces the quality and quantity of sleep, and greater sleep loss over the lifespan is predictive of neurodegeneration and cognitive decline. One mechanism by which sleep loss could contribute to impaired brain health is through disruption of cerebrospinal fluid (CSF) circulation. CSF is the primary waste transport system of the brain, and in young adults, CSF waves are largest during NREM sleep. However, whether sleep-dependent brain fluid physiology changes in aging is not known, due to the technical challenges of performing neuroimaging studies during sleep. We collected simultaneous fast fMRI and EEG data to measure large-scale CSF flow in healthy young and older adults and tested whether there were age-related changes to CSF dynamics during nighttime sleep. We found that sleep-dependent CSF flow was reduced in older adults, and this reduction was linked to impaired frontal EEG delta power and global hemodynamic oscillations during sleep. To identify mechanisms underlying reduced CSF flow, we used sensory and vasoactive stimuli to drive CSF flow in daytime task experiments, and found that both neural and cerebrovascular physiological changes contributed to the disruption of CSF flow during sleep. Finally, we found that this reduction in CSF flow was associated with gray matter atrophy in aging. Together, these results demonstrate that the aging human brain has reduced CSF flow during sleep, and identifies underlying neurovascular mechanisms that contribute to this age-related decline, suggesting targets for future interventions.

Bidirectional causal associations between frailty measures and sleep disturbances: a two-sample Mendelian randomization study

Background

Observational studies have demonstrated a strong association between sleep disturbances and frailty. However, the causality remains inconclusive. We aimed to investigate the bidirectional causal relationships between frailty measures and sleep disturbances employing a two-sample Mendelian randomization (MR) analysis.

Methods

Two-sample MR analyses were performed based on large-scale genome-wide association studies (GWAS) of the European population for frailty index (FI) (N = 175,226), Fried Frailty Score (FFS) (N = 386,565), insomnia (N = 283,595), sleep duration (N = 445,966) and sleep apnea (N = 523,366). We conducted the causal estimates using the inverse variance-weighted method (IVW), with sensitivity analyses using MR-Egger, weighted median, weighted mode, and MR pleiotropy residual sum and outlier (MR-PRESSO) analysis. Cochran's Q test was performed to assess heterogeneity.

Results

We found that genetically predicted FI was associated with shorter sleep duration and sleep apnea. The genetically predicted FFS was associated with insomnia, shorter sleep duration, and sleep apnea. In the reverse direction analysis, genetic liability to insomnia, short sleep duration, and long sleep duration were associated with an increase in FI. Genetic liability to short sleep duration and long sleep duration were associated with an increase in FFS.

Conclusion

Our study provided genetic evidence supporting the bidirectional causality between frailty measures and sleep disturbances. The findings contribute to the prevention and management of frailty and sleep disturbances.

Characterisation of nocturnal arrhythmia avalanche dynamics: Insights from generalised linear model analysis

Nocturnal arrhythmia avalanche (NAA) episodes, characterised by transient non-sustained cardiac arrhythmias during sleep, have been demonstrated as a predictor of adverse cardiovascular events. However, their dynamics and association with sleep architecture and events remain unclear. While generalised linear models (GLM) have captured sleep-disordered breathing (SDB) dynamics, their application to NAA remains underexplored. This study explored whether changes in sleep architecture contribute to nocturnal arrhythmias and if the impact of sleep stages, SDB, and arousal events on these arrhythmias varies by demographic factors. We analysed 7341 ECG recordings from the multi-ethnic study of atherosclerosis (MESA) and the sleep heart health study (SHHS) datasets. R-R intervals were divided into 10-min periods to detect NAA, defined as a 30% drop from baseline followed by recovery to 90% of baseline. A GLM framework was developed to characterise NAA episodes as functions of SDB, sleep arousal events, sleep stages, and prior NAA episodes. The GLM analysis revealed that NAA occurrence was 18% and 30% higher during non-rapid eye movement (NREM) light sleep compared with deep sleep in SHHS (p < 0.001) and MESA (p < 0.001), respectively. SDB events increased the NAA risk in 34% of participants, and arousals in 29%. In SHHS, the impact of SDB on NAA was 5% greater in men (p = 0.018), while the arousal effects were more pronounced in those over 75, highlighting the role of demographic factors in modulating arrhythmia risk. These findings demonstrate the utility of the GLM framework in modelling the dynamics of nocturnal arrhythmias and their associations with sleep disruptions and architecture.

Sleep spindles and slow oscillations predict cognition and biomarkers of neurodegeneration in mild to moderate Alzheimer's disease

INTRODUCTION

Changes in sleep physiology can predate cognitive symptoms by decades in persons with Alzheimer's disease (AD), but it remains unclear which sleep characteristics predict cognitive and neurodegenerative changes after AD onset.

METHODS

Using data from a prospective cohort of mild to moderate AD (n = 60), we analyzed non-rapid eye movement sleep spindles and slow oscillations (SOs) at baseline and their associations with baseline amyloid beta (Aβ) and tau and with cognition from baseline to 3-year follow-up.

RESULTS

Higher spindle and SO activity predicted significant changes in Aβ and tau at baseline, lower Alzheimer's Disease Assessment Scale Cognitive Subscale (better cognitive performance) score, and higher Mini-Mental State Examination score from baseline to 36 months. Spindles and SOs mediated the effect of phosphorylated tau 181 (pTau181)/Aβ42 on cognition, while pTau181/aβ42 moderated the effect of spindles and SOs on cognition.

DISCUSSION

Our findings demonstrate that spindle and SO activity during sleep constitute predictive and non-invasive biomarkers of neurodegeneration and cognition in AD patients.

HIGHLIGHTS

Sleep spindles predict long-term cognitive performance in AD. Sleep spindle and SOs can be predictive, non-invasive biomarkers for AD. Sleep may be one of the most important modifiable risk factors for AD progression. Sleep microarchitecture is a novel therapeutic target for preserving brain heath. Sleep physiology can provide novel therapeutic targets to slow AD progression.

The effect of sleep disturbances on the incidence of dementia for varying lag times

BACKGROUND

Few studies have addressed the association of sleep disturbances with incident dementia with long lag times. We add to this literature by investigating how lag times varying from 2.2 to 23.8 years affect the relationship between sleep disturbance and incident dementia in a Dutch cohort study on aging.

METHODS

Using eight waves of data from the Longitudinal Aging Study Amsterdam, we investigated the association of hours of sleep, difficulty falling asleep, interrupted sleep, and waking up early with incident dementia. For dementia an algorithm was used based on repeated measurements of cognitive tests and other data sources that provide strong indications of dementia. Sleep disturbances were assessed with a self-report questionnaire.

RESULTS

Of 2,218 participants, 237 (11%) developed dementia in the period 1992/3 to 2015/6. Participants ≥70 years more often reported sleep disturbances compared to those <70. Only for a short lag time (3 years), sleeping ≥9 h was associated with incident dementia. Sleeping ≤6 h, interrupted sleep and waking up early were associated with incident dementia, particularly for lag times ≥15 years.

DISCUSSION

We found that the association of sleep disturbances with incident dementia becomes stronger with longer lag times (particularly ≥15 years). Studies with lag times <15 years may suffer from reverse causation due to the changes in sleep patterns caused by the prodromal phase of neurodegenerative disease. The association of sleeping ≥9 h and the incidence of dementia in analyses with a short lag time seem to be the result of reverse causation.

Pandemic policies and sleeping problems in older adults

Sleep quality is fundamental to physical and mental health. Recent research shows that the COVID-19 pandemic has affected individuals' sleep quality. This study aims to investigate whether the containment and health policies (Oxford Coronavirus Government Response Tracker indexes) adopted by European countries and Israel during the pandemic are related to sleep problems in people aged 50 and over. A cross-sectional study was conducted using a logistic regression analysis based on data from the Survey of Health, Ageing and Retirement in Europe, collected in 27 European countries and Israel, in 2021. The results show that containment and health policies affect older adults' sleep, once we neutralise the influence of the sociodemographic, economic, and health characteristics of the individuals and close contact with COVID-19. In fact, the more containment and health policies, the fewer chances of sleep problems. A possible explanation for this is that these policies give people over 50 a sense of safety and security in relation to COVID-19, which may reduce sleep problems.

Automated remote sleep monitoring needs uncertainty quantification

Wearable electroencephalography devices emerge as a cost-effective and ergonomic alternative to gold-standard polysomnography, paving the way for better health monitoring and sleep disorder screening. Machine learning allows to automate sleep stage classification, but trust and reliability issues have hampered its adoption in clinical applications. Estimating uncertainty is a crucial factor in enhancing reliability by identifying regions of heightened and diminished confidence. In this study, we used an uncertainty-centred machine learning pipeline, U-PASS, to automate sleep staging in a challenging real-world dataset of single-channel electroencephalography and accelerometry collected with a wearable device from an elderly population. We were able to effectively limit the uncertainty of our machine learning model and to reliably inform clinical experts of which predictions were uncertain to improve the machine learning model's reliability. This increased the five-stage sleep-scoring accuracy of a state-of-the-art machine learning model from 63.9% to 71.2% on our dataset. Remarkably, the machine learning approach outperformed the human expert in interpreting these wearable data. Manual review by sleep specialists, without specific training for sleep staging on wearable electroencephalography, proved ineffective. The clinical utility of this automated remote monitoring system was also demonstrated, establishing a strong correlation between the predicted sleep parameters and the reference polysomnography parameters, and reproducing known correlations with the apnea-hypopnea index. In essence, this work presents a promising avenue to revolutionize remote patient care through the power of machine learning by the use of an automated data-processing pipeline enhanced with uncertainty estimation.

Sleep onset time as a mediator in the association between screen exposure and aging: a cross-sectional study

Excessive screen exposure has become a significant health concern. This study investigates the impact of screen time on aging in middle-aged and elderly populations. Healthy working adults over 45 years old in Shanghai, China, underwent general and ocular examinations. Questionnaires collected demographics, medical history, and screen exposure details. Aging was assessed using the retinal age gap, defined as the difference between the retinal age predicted by deep learning algorithms based on fundus images and chronological age. Pathway analysis tested the mediation effect of sleep duration and onset time on the relationship between screen usage and retinal age gap. The retinal age gap increased with longer screen exposure, from 0.49 ± 3.51 years in the lowest tertile to 5.13 ± 4.96 years in the highest tertile (Jonckheere-Terpstra test, p < 0.001). Each additional hour of screen exposure accelerated the retinal age gap by 0.087 years (95% CI, 0.027, 0.148, p = 0.005) in the fully adjusted linear model. Sleep onset time mediated the impact of screen usage on the retinal age gap (indirect effect, β = 0.11; 95% CI 0.04-0.24). The impact of screen usage in a light-off environment on the retinal age gap was fully mediated by sleep onset time (indirect effect, β = 0.22; 95% CI 0.07-0.38), with the proportion being 100%. Our study identified a correlation between excessive screen time and a wider retinal age gap in middle-aged and elderly individuals, likely due to delayed sleep onset. To mitigate the adverse effects on the retina and aging, it is important to limit screen usage and avoid screens before bedtime.

Genetic causality between insomnia and specific orthopedic conditions: Insights from a two-sample Mendelian randomization study

OBJECTIVE

To investigate the genetic causality for the insomnia and common orthopedic diseases, such as rheumatoid arthritis (RA), ankylosing spondylitis (AS), osteoporosis (OP), and gout (GT).

METHODS

The genome-wide association study (GWAS) summary data on insomnia were obtained from a published study, while the GWAS summary data on RA, AS, OP, and GT were sourced from the FinnGen consortium. We utilized the TwoSampleMR package of the R software (version 4.1.2) to conduct a two-sample Mendelian randomization (MR) analysis. Our primary method of analysis was the random-effects inverse variance weighted (IVW) approach. Subsequently, we conducted a series of sensitivity analyses for the MR analysis.

RESULTS

The MR analysis revealed a positive genetic causal relationship between insomnia and RA (P = 0.016, odds ratio [OR] 95 % confidence interval [CI] = 1.112 [1.020-1.212]). However, no significant genetic causal relationship was observed between insomnia and AS (P = 0.194, OR 95 % CI = 1.121 [0.944-1.331]), OP (P = 0.788, OR 95 % CI = 1.016 [0.904-1.142]), and GT (P = 0.757, OR 95 % CI = 1.018 [0.912-1.136]). The MR analysis did not exhibit heterogeneity, horizontal pleiotropy, outlier effects, or dependence on a single SNP, and demonstrated normal distribution, which guaranteed the robustness of the results.

CONCLUSION

The results of this study suggest that insomnia may be a significant risk factor for RA, and controlling insomnia may represent a promising strategy for preventing RA. While insomnia was not observed to be associated with AS, OP, and GT at the genetic level, other levels of association cannot be excluded.