Age and gender variations of sleep in subjects without sleep disorders

Insomnia symptoms and increased risk of all-cause mortality by age and sex

STUDY OBJECTIVES

Prior research suggests that insomnia may increase the risk of death. However, the potential influence of age and sex is unclear. This study aimed to investigate the association of insomnia symptoms with all-cause mortality by age and sex.

METHODS

This prospective cohort was drawn from the Health and Retirement Study, a survey of Americans older than 50 years and their spouses of any age from 2002-2018. Insomnia symptom scores were based on difficulties initiating sleep, difficulty maintaining sleep, waking up too early, and nonrestorative sleep. Cox proportional-hazards regression models were employed to investigate the association between insomnia symptoms and all-cause mortality stratified by age and sex.

RESULTS

A total of 33,004 participants were included with a mean age of 61.7 years and 56.8% females. Over a mean follow-up of 8.4 years, 8,935 (27.1%) deaths were recorded. After adjusting for confounding, males with insomnia symptom scores ranging from 5-8 had a 71% increased risk of death (hazard ratio = 1.71; 95% confidence interval: 1.27, 2.30) compared with their counterparts without insomnia symptoms. Similarly, males aged ≥ 60 years and females aged < 60 years with insomnia symptoms ranging from 5-8 had an increased risk of death compared with their counterparts without insomnia symptoms (hazard ratio = 1.15; 95% confidence interval: 1.02, 1.31 and hazard ratio = 1.38; 95% confidence interval: 1.00, 1.90, respectively). However, there was no increased risk of death for females aged ≥ 60 years (hazard ratio = 0.94; 95% confidence interval: 0.84, 1.06).

CONCLUSIONS

These findings suggest that insomnia symptoms may serve as predictors of low life expectancy.

CITATION

Sawadogo W, Adera T. Insomnia symptoms and increased risk of all-cause mortality by age and sex. J Clin Sleep Med. 2024;20(10):1585-1593.

The effects of daylight duration on the multiple sleep latency test (MSLT) results: A pilot study

OBJECTIVE

MSLT results are known to be affected by multiple factors including sleep time, frequency of nighttime arousals, and medications intake. Although being the main synchronizer of sleep and wakefulness, daylight duration effects on MSLT have not been examined. Burlington, Vermont, USA experiences great variations in daylight duration, ranging from 8 h 50 min to 15 h 33 min of daylight. The aim of this study was to test the hypothesis that there would be photoperiod duration effects on MSLTs performed during short daylight (short daylight studies, SDS) vs. long daylight (long daylight studies, LDS) from 2013 to 2023 in our sleep laboratory.

METHODS

We identified and analyzed 37 SDS (daylight 530-560 min) and 36 LDS (daylight 903-933 min) from our database. Groups of SDS and LDS results were compared using non-paired student T test, Chi-Square and non-parametric Mann Whitney U Test.

RESULTS

Average daylight duration was 15 h 18 ± 14.6 min for LDS and 8 h 57 ± 18 min for SDS. Two groups did not differ in terms of the age, gender, BMI and race of patients studied. Mean total sleep time and sleep efficiency during PSG preceding MSLT, and MSLT mean sleep onset latency did not significantly differ for the two groups. However, SDS MSLT naps had significantly more sleep onset REM periods (SOREMP), and distribution of the number of SOREMP captured during MSLT was different for SDS and LDS groups. Differences of SDS and LDS results did not relate to sleep architecture of the overnight PSG as analysis of sleep and REM latency and relative percentages of N1, N2, REM, and N3 was not significantly different between SDS and LDS. The two groups showed difference in arousal indexes during N1 and REM sleep.

CONCLUSIONS

Daylight duration may impact MSLT results and should probably be accounted for in MSLT interpretation. Attention to photoperiod could be considered in MSLT guidelines, if our results are replicated in larger samples.

Sleep disturbance in rodent models and its sex-specific implications

Sleep disturbances, encompassing altered sleep physiology or disorders like insomnia and sleep apnea, profoundly impact physiological functions and elevate disease risk. Despite extensive research, the underlying mechanisms and sex-specific differences in sleep disorders remain elusive. While polysomnography serves as a cornerstone for human sleep studies, animal models provide invaluable insights into sleep mechanisms. However, the availability of animal models of sleep disorders is limited, with each model often representing a specific sleep issue or mechanism. Therefore, selecting appropriate animal models for sleep research is critical. Given the significant sex differences in sleep patterns and disorders, incorporating both male and female subjects in studies is essential for uncovering sex-specific mechanisms with clinical relevance. This review provides a comprehensive overview of various rodent models of sleep disturbance, including sleep deprivation, sleep fragmentation, and circadian rhythm dysfunction. We evaluate the advantages and disadvantages of each model and discuss sex differences in sleep and sleep disorders, along with potential mechanisms. We aim to advance our understanding of sleep disorders and facilitate sex-specific interventions.

Active Inflammatory Bowel Disease Is Associated with Short Sleep Duration via Objective Measures

INTRODUCTION

Poor sleep quality has been associated with inflammatory bowel disease (IBD) activity, although studies incorporating actigraphy suggest that the perception of sleep differs rather than objective difference in sleep quality. Short sleep duration has been associated with increased pro-inflammatory cytokines that have been implicated in the pathogenesis of IBD.

METHODS

An observational study incorporated home-based polysomnography that was conducted within twelve weeks of an objective assessment of IBD activity such as calprotectin, colonoscopy, or MRI. Participants completed a survey on subjective measures of sleep quality, clinical IBD activity, depression, and anxiety. Polysomnography results were normalized by standardized results for a healthy population matched by gender and age.

RESULTS

Twenty participants were included in the final analysis. Those with objective evidence of active IBD had shorter stage 2 sleep duration, leading to shorter NREM sleep and total sleep time. Sleep latency was also longer in those with active IBD, leading to worse sleep efficiency-despite no difference in time available for sleep between the two groups. These changes persisted after normalization of polysomnography results by health population age and gender matched norms. Depression scores correlated with sleep latency and stage 2 sleep duration and were associated with objectively active IBD.

CONCLUSIONS

Objectively confirmed active IBD was associated with shorter sleep duration. Observed sleep changes may, in part, relate to coexistent depression. Further research should consider the utility of changes in sleep duration and quality as a means of longitudinally assessing objective IBD activity.

Sex differences in sleep, circadian rhythms, and metabolism: Implications for precision medicine

The number of individuals experiencing sleep loss has exponentially risen over the past decades. Extrapolation of laboratory findings to the real world suggests that females are more affected by extended wakefulness and circadian misalignment than males are. Therefore, long-term effects such as sleep and metabolic disorders are likely to be more prevalent in females than in males. Despite emerging evidence for sex differences in key aspects of sleep-wake and circadian regulation, much remains unknown, as females are often underrepresented in sleep and circadian research. This narrative review aims at highlighting 1) how sex differences systematically impinge on the sleep-wake and circadian regulation in humans, 2) how sex differences in sleep and circadian factors modulate metabolic control, and 3) the relevance of these differences for precision medicine. Ultimately, the findings justify factoring in sex differences when optimizing individually targeted sleep and circadian interventions in humans.

Nurses' level of sleepiness during night shift

AIMS

This study aimed to determine the peak hours of sleepiness and the factors affecting the sleepiness levels of nurses.

BACKGROUND

Sleepiness is commonly seen in individuals working night shifts. However, in case of nurses, this sleepiness can be a major threat to patient and staff safety.

METHOD

This was a prospective cross-sectional study. Data were collected between July and September 2023, and a stratified sampling method was used according to the departments in which the nurses worked. Data were collected using the Personal Information Form and Visual Analog Scale. Nurses reported their sleepiness levels at the beginning of each hour between midnight and 8:00 am.

EQUATOR CHECKLIST

The study adhered to the STROBE checklist for reporting.

RESULTS

The mean sleepiness levels of emergency department nurses, intensive care nurses, internal or surgical clinic nurses, and all nurses were 59.75 ± 15.50, 43.53 ± 20.49, 44.67 ± 18.88, and 49.15 ± 19.67, respectively. The highest sleepiness level of the nurses was at 05:00 am. A significant correlation was found between the variables of age, gender, marital status, sleep quality, number of patients cared, working style and satisfaction with working in the department, and sleepiness level (P < 0.05).

CONCLUSION

Nurses working night shifts experience sleepiness (highest at 5:00 am). In addition, the sleepiness levels of nurses are affected by some personal and clinical factors.

IMPLICATIONS FOR NURSING AND NURSING POLICY

Based on the results, there is a need for necessary policies regarding nurses' working hours and working conditions. To protect patient and employee safety, necessary strategies should be devised regarding the hours when nurses experience the highest sleepiness and the factors affecting sleepiness levels.

Predictors and disturbances of sleep quality between men and women: results from a cross-sectional study in Jordan

BACKGROUND

Sleep disturbances, a public health concern that may lead to critical physiological conditions, are associated with personal characteristics such as gender. Limited evidence is available from the Middle East population on the gender disparities in sleep quality. Therefore, the current study examined gender-specific differences in sleep quality and disturbances among Jordanian citizens.

METHOD

A cross-sectional design was used to recruit a convenient sample of 1,092 adults from different Jordanian cities. Data was collected using a self-reported questionnaire comprising the Pittsburgh Sleep Quality Index (PSQI), which was distributed online via social media networks. The participants were categorized according to their global PSQI scores into poor (PSQI ≥ 5) and good sleepers (PSQI < 5). The analysis focused on finding differences between women and men in terms of sleep quality and the effects of demographic, lifestyle, and socioeconomic factors on reported sleep problems.

RESULTS

Women were revealed to have a higher prevalence of all types of sleep disturbances than men. Women who were over 55 (compared to younger than 20 years), did not smoke, had multiple jobs or part-time employment (compared to unemployed women), and had a monthly income of more than 500 JD (compared to those with an income of < 500 JD) were less likely to experience poor sleep than other women. In contrast, men who neither smoked nor drank coffee, ate no sweets or only one to two pieces daily (compared to participants who ate more than two pieces daily), and worked fixed night shifts (compared to alternating shifts workers) were less likely to experience poor sleep than other men.

CONCLUSION

This study builds a more nuanced understanding of how different demographic, lifestyle, and socioeconomic factors - such as a participant's age, time of working duty, income, daily sweet consumption, daily caffeine consumption, and smoking - affect the sleep quality of men and women. Thus, promoting a healthier lifestyle for both genders by modifying risk factors - such as smoking cessation, as well as reducing their intake of caffeine and sweets - is the first step toward improving their sleep quality. Further studies are needed to examine how the social role of Arabic women affects their sleep.

Efficacy of transcranial alternating current stimulation in treating chronic insomnia and the impact of age on its effectiveness: A multisite randomized, double-blind, parallel-group, placebo-controlled study

OBJECTIVE

Insomnia is a significant health issue associated with various systemic diseases. Transcranial alternating current stimulation (tACS) has been proposed as a potential intervention for insomnia. However, the efficacy and mechanisms of tACS in chronic insomnia remain unclear. Accordingly, this study aimed to investigate the efficacy of tACS in treating chronic insomnia in adults and assess the impact of age on its effectiveness using a large sample from two centers.

METHODS

A total of 120 participants with chronic insomnia underwent 20 daily sessions of tACS (duration: 40 min, frequency: 77.5 Hz, and intensity: 15 mA) or sham tACS targeting the forehead and both mastoid areas over 4 weeks. Assessments were conducted at baseline, post-treatment, and 4-week follow-up. Primary outcomes included sleep quality and efficiency, onset latency, total sleep time, and daily disturbances. Secondary outcomes included depression, anxiety, and clinical impression.

RESULTS

Compared with the control group, the tACS group demonstrated improved sleep quality and efficiency, increased total sleep time, and reduced daily disturbance (all ps < 0.01). Moreover, tACS had a significant effect on clinical impression (p < 0.001), but not depression and anxiety scores. Subgroup analyses revealed that older participants experienced significant benefits from tACS in sleep quality, efficiency, and overall insomnia reduction at post-treatment and follow-up (p < 0.001). Notably, improved insomnia correlated with attenuated depressive and anxiety symptoms.

CONCLUSIONS

These findings suggest that tACS may be an effective intervention for chronic insomnia within an eight-week timeframe, and age affects the response to tACS in terms of insomnia improvement.

Evaluating sleep-stage classification: how age and early-late sleep affects classification performance

Sleep stage classification is a common method used by experts to monitor the quantity and quality of sleep in humans, but it is a time-consuming and labour-intensive task with high inter- and intra-observer variability. Using wavelets for feature extraction and random forest for classification, an automatic sleep-stage classification method was sought and assessed. The age of the subjects, as well as the moment of sleep (early-night and late-night), were confronted to the performance of the classifier. From this study, we observed that these variables do affect the automatic model performance, improving the classification of some sleep stages and worsening others.

Gender differences in the relationship between sleep and age in a Brazilian cohort: the Baependi Heart Study

Gender and age are well-established determinants of health and sleep health that influence overall health, which also often varies by gender and age. Sleep architecture is an important component of sleep health. The goal of this analysis was to examine whether associations between age and sleep stages differ by gender in the absence of moderate-severe obstructive sleep apnea (OSA) in a rural setting in Brazil. This study conducted polysomnography recordings in the Baependi Heart Study, a cohort of Brazilian adults. Our sample included 584 women and 309 men whose apnea-hypopnea index was ≤15 events/h. We used splines to distinguish non-linear associations between age, total sleep time, wake after sleep onset (WASO), N2, N3, and rapid-eye-movement sleep. The mean (standard deviation; range) age was 47 (14; 18-89) years. All sleep outcomes were associated with age. Compared to men, women had more N3 sleep and less WASO after adjusting for age. Model-based comparisons between genders at specific ages showed statistically higher mean WASO for men at ages 60 (+13.6 min) and 70 years (+19.5 min) and less N3 for men at ages 50 (-13.2 min), 60 (-19.0 min), and 70 years (-19.5 min) but no differences at 20, 30, 40 or 80 years. The other sleep measures did not differ by gender at any age. Thus, even in the absence of moderate-severe OSA, sleep architecture was associated with age across adulthood, and there were gender differences in WASO and N3 at older ages in this rural community.

Sex Differences in Sleep Architecture After Traumatic Brain Injury: Potential Implications on Short-Term Episodic Memory and Recovery

Sleep-wake disturbances (SWDs) are common after TBI and often extend into the chronic phase of recovery. Such disturbances in sleep can lead to deficits in executive functioning, attention, and memory consolidation, which may ultimately impact the recovery process. We examined whether SWDs post-TBI were associated with morbidity during the post-acute period. Particular attention was placed on the impact of sleep architecture on learning and memory. Because women are more likely to report SWDs, we examined sex as a biological variable. We also examined subjective quality of life, depression, and disability levels. Data were retrospectively analyzed for 57 TBI patients who underwent an overnight polysomnography. Medical records were reviewed to determine cognitive and functional status during the period of the sleep evaluation. Consideration was given to medications, owing to the fact that a high number of these are likely to have secondary influences on sleep characteristics. Women showed higher levels of disability and reported more depression and lower quality of life. A sex-dependent disruption in sleep architecture was observed, with women having lower percent time in REM sleep. An association between percent time in REM and better episodic memory scores was found. Melatonin utilization had a positive impact on REM duration. Improvements in understanding the impact of sleep-wake disturbances on post-TBI outcome will aid in defining targeted interventions for this population. Findings from this study support the hypothesis that decreases in REM sleep may contribute to chronic disability and underlie the importance of considering sex differences when addressing sleep.

Reduced overnight memory consolidation and associated alterations in sleep spindles and slow oscillations in early Alzheimer's disease

Spatial navigation critically underlies hippocampal-entorhinal circuit function that is early affected in Alzheimer's disease (AD). There is growing evidence that AD pathophysiology dynamically interacts with the sleep/wake cycle impairing hippocampal memory. To elucidate sleep-dependent consolidation in a cohort of symptomatic AD patients (n = 12, 71.25 ± 2.16 years), we tested hippocampal place learning by means of a virtual reality task and verbal memory by a word-pair association task before and after a night of sleep. Our results show an impaired overnight memory retention in AD compared with controls in the verbal task, together with a significant reduction of sleep spindle activity (i.e., lower amplitude of fast sleep spindles, p = 0.016) and increased duration of the slow oscillation (SO; p = 0.019). Higher spindle density, faster down-to-upstate transitions within SOs, and the time delay between SOs and nested spindles predicted better memory performance in healthy controls but not in AD patients. Our results show that mnemonic processing and memory consolidation in AD is slightly impaired as reflected by dysfunctional oscillatory dynamics and spindle-SO coupling during NonREM sleep. In this translational study based on experimental paradigms in animals and extending previous work in healthy aging and preclinical disease stages, our results in symptomatic AD further deepen the understanding of the memory decline within a bidirectional relationship of sleep and AD pathology.

Sex and Sleep Disruption as Contributing Factors in Alzheimer's Disease

Alzheimer's disease (AD) affects more women than men, with women throughout the menopausal transition potentially being the most under researched and at-risk group. Sleep disruptions, which are an established risk factor for AD, increase in prevalence with normal aging and are exacerbated in women during menopause. Sex differences showing more disrupted sleep patterns and increased AD pathology in women and female animal models have been established in literature, with much emphasis placed on loss of circulating gonadal hormones with age. Interestingly, increases in gonadotropins such as follicle stimulating hormone are emerging to be a major contributor to AD pathogenesis and may also play a role in sleep disruption, perhaps in combination with other lesser studied hormones. Several sleep influencing regions of the brain appear to be affected early in AD progression and some may exhibit sexual dimorphisms that may contribute to increased sleep disruptions in women with age. Additionally, some of the most common sleep disorders, as well as multiple health conditions that impair sleep quality, are more prevalent and more severe in women. These conditions are often comorbid with AD and have bi-directional relationships that contribute synergistically to cognitive decline and neuropathology. The association during aging of increased sleep disruption and sleep disorders, dramatic hormonal changes during and after menopause, and increased AD pathology may be interacting and contributing factors that lead to the increased number of women living with AD.

Region-specific changes in brain activity and memory after continuous positive airway pressure therapy in obstructive sleep apnea: a pilot high-density electroencephalography study

STUDY OBJECTIVES

Limited channel electroencephalography (EEG) investigations in obstructive sleep apnea (OSA) have revealed deficits in slow wave activity (SWA) and spindles during sleep and increased EEG slowing during resting wakefulness. High-density EEG (Hd-EEG) has also detected local parietal deficits in SWA (delta power) during NREM. It is unclear whether effective continuous positive airway pressure (CPAP) treatment reverses regional SWA deficits, and other regional sleep and wake EEG abnormalities, and whether any recovery relates to improved overnight memory consolidation.

METHODS

A clinical sample of men with moderate-severe OSA underwent sleep and resting wake recordings with 256-channel Hd-EEG before and after 3 months of CPAP. Declarative and procedural memory tasks were administered pre- and post-sleep. Topographical spectral power maps and differences between baseline and treatment were compared using t-tests and statistical nonparametric mapping (SnPM).

RESULTS

In 11 compliant CPAP users (5.2 ± 1.1 hours/night), total sleep time did not differ after CPAP but N1 and N2 sleep were lower and N3 was higher. Centro-parietal gamma power during N3 increased and fronto-central slow spindle activity during N2 decreased (SnPM < 0.05). No other significant differences in EEG power were observed. When averaged specifically within the parietal region, N3 delta power increased after CPAP (p = 0.0029) and was correlated with the change in overnight procedural memory consolidation (rho = 0.79, p = 0.03). During resting wakefulness, there were trends for reduced delta and theta power.

CONCLUSIONS

Effective CPAP treatment of OSA may correct regional EEG abnormalities, and regional recovery of SWA may relate to procedural memory improvements in the short term.

Dusk2Dawn: an EEGLAB plugin for automatic cleaning of whole-night sleep electroencephalogram using Artifact Subspace Reconstruction

Whole-night sleep electroencephalogram (EEG) is plagued by several types of large-amplitude artifacts. Common approaches to remove them are fraught with issues: channel interpolation, rejection of noisy intervals, and independent component analysis are time-consuming, rely on subjective user decisions, and result in signal loss. Artifact Subspace Reconstruction (ASR) is an increasingly popular approach to rapidly and automatically clean wake EEG data. Indeed, ASR adaptively removes large-amplitude artifacts regardless of their scalp topography or consistency throughout the recording. This makes ASR, at least in theory, a highly-promising tool to clean whole-night EEG. However, ASR crucially relies on calibration against a subset of relatively clean "baseline" data. This is problematic when the baseline changes substantially over time, as in whole-night EEG data. Here we tackled this issue and, for the first time, validated ASR for cleaning sleep EEG. We demonstrate that ASR applied out-of-the-box, with the parameters recommended for wake EEG, results in the dramatic removal of slow waves. We also provide an appropriate procedure to use ASR for automatic and rapid cleaning of whole-night sleep EEG data or any long EEG recording. Our procedure is freely available in Dusk2Dawn, an open-source plugin for EEGLAB.

Relationship between CGM-derived nocturnal hypoglycemia and subjective sleep quality in people with type 1 diabetes

This pilot study explores the relationship between nocturnal hypoglycemia (NH) and subjective sleep quality in people with type 1 diabetes (T1D). Twenty-seven adults with T1D wore a Freestyle Libre Pro CGM and recorded subjective sleep quality daily, as assessed by a single Likert scale question. Frequency, duration, area under the curve (AUC) of NH (00:00-06:00) defined as sensor glucose below threshold (< 3.9 mmol/L; < 3 mmol/L) for ≥ 15 min, nocturnal mean glucose, Time in Range (3.9-10 mmol/L), and coefficient of variation were calculated. Twenty-seven adults, 18 (66.7%) women, with median (IQR) age of 27 (26, 32) years and HbA1c of 7.6 (7.1, 8.1) participated. Nights with NH < 3.9 mmol/L resulted in a lower (worse) sleep score than nights without NH [Mean (SD): 3.3 (1.2) vs 3.5 (1.0), p = 0.03). A higher frequency and longer duration but not AUC [adjusted OR (95% CI) 0.52 (0.38, 0.72), 0.961 (0.932, 0.991), 0.999 (0.998, 1.001) respectively)], of NH < 3.9 mmol/L, were associated with a lower sleep score. NH < 3.0 mmol/L metrics were not associated with sleep quality. Recurrent NH < 3.9 mmol/L, rather than prolonged NH < 3.0 mmol/L, seems associated with subjective sleep quality, implying that those with the highest burden of NH are likely unaware of it.

Sleep and memory consolidation in aging: A neuroimaging perspective

Recently acquired information is strengthened and consolidated during sleep. For hippocampus-dependent memory, this process is assumed to occur mainly during slow wave sleep. Changes in sleep patterns in older adults can contribute to the disruption of the consolidation process during sleep and thus lead to cognitive impairment. Current findings suggest that reduced gray matter volume, particularly in frontal areas, Aβ and tau accumulation in combination with age-related changes of specific oscillations during sleep may contribute to memory deficits. This non-exhaustive review aims at providing a comprehensive picture of the associations between sleep changes and memory consolidation in aging, mainly based on neuroimaging studies. Overall, data confirm the utmost importance of sleep for healthy aging and the need to develop interventions aiming at improving sleep to reduce cognitive decline observed with advancing age.

Normal multiple sleep latency test values in adults: A systematic review and meta-analysis

Sleep latency is a measure of time it takes to enter sleep. Very short sleep latencies are indicative of excessive daytime sleepiness and pathological sleep conditions such as narcolepsy. The normal range of mean sleep latency calculated from the multiple sleep latency test in healthy adults is not well-established. We provide a review of normative mean sleep latency values on the multiple sleep latency test by synthesizing data from 110 healthy adult cohorts. We also examine the impact of demographic variables such as age, sex, body mass index, sleep architecture and sleep-disordered breathing as well as methodological variables such as sleep onset definitions and multiple sleep latency test protocols. The average mean sleep latency was 11.7 min (95% CI: 10.8-12.6; 95% PI: 5.2-18.2) for cohorts evaluated using the earlier definition of sleep onset and 11.8 min (95% CI: 10.7-12.8; 95% PI: 7.2-16.3) for those evaluated using the later definition. There were no significant associations between mean sleep latency and demographic or methodological variables. A negative association of -0.29 per one unit increase (95% CI: -0.55 to -0.04) was found between mean sleep latency and apnea-hypopnea index on prior night polysomnography. Establishing updated ranges for mean sleep latency among healthy adults may guide clinical decision-making surrounding sleep pathologies and inform future research into the associations between patient variables, daytime sleepiness, and sleep pathologies.

How emotions induced by reading influence sleep quality in young and older adults

OBJECTIVES

This study examined whether emotions induced by reading before sleep influence sleep quality in young and older adults.

METHOD

Sixty older adults (64-75 years) and 60 young adults (18-35 years) were randomly assigned to three conditions: positive reading, neutral reading, and control. The reading groups read a short story at bedtime, whereas the control group kept its routine. Participants completed measures of affective states, subjective sleep parameters, and self-reported sleep quality related to emotions over 7 consecutive days.

RESULTS

Older adults reported much longer sleep latency and lower sleep efficiency than young adults. In both reading conditions, older adults reported reduced sleep latencies compared to the control group. In the positive reading condition, older adults reported an increased sleep duration compared to younger adults and the other conditions. Young and older adults in the positive condition showed better self-reported sleep quality than those in the neutral conditions, regardless of age.

CONCLUSIONS

Reading at bedtime appears to reduce older adults' time to fall asleep and increase their sleep duration. Positive emotions induced by reading short stories at bedtime seem to be a sleep-promoting factor that improves bedtime and wake time in young and older adults.

Decoding information about cognitive health from the brainwaves of sleep

Sleep electroencephalogram (EEG) signals likely encode brain health information that may identify individuals at high risk for age-related brain diseases. Here, we evaluate the correlation of a previously proposed brain age biomarker, the "brain age index" (BAI), with cognitive test scores and use machine learning to develop and validate a series of new sleep EEG-based indices, termed "sleep cognitive indices" (SCIs), that are directly optimized to correlate with specific cognitive scores. Three overarching cognitive processes were examined: total, fluid (a measure of cognitive processes involved in reasoning-based problem solving and susceptible to aging and neuropathology), and crystallized cognition (a measure of cognitive processes involved in applying acquired knowledge toward problem-solving). We show that SCI decoded information about total cognition (Pearson's r = 0.37) and fluid cognition (Pearson's r = 0.56), while BAI correlated only with crystallized cognition (Pearson's r = - 0.25). Overall, these sleep EEG-derived biomarkers may provide accessible and clinically meaningful indicators of neurocognitive health.

Sleep Quality Moderates the Relationship Between Daily Mean Levels and Variability of Positive Affect

Despite the well-established bidirectional association between sleep and daytime affect, most studies examining this relationship have focused on mean levels of affect. However, research solely focusing on mean levels of affect inherently neglects variability in affect, which has been shown to predict both psychological and physical well-being beyond mean levels. The present study assessed sleep quality and daytime affect using ecological momentary assessment in a combined sample of individuals (N = 80; 8,881 observations) with and without anxiety and mood disorders. Results from the present study partially replicated extant work on the negative association between negative affect (NA) variability and subsequent sleep quality. Furthermore, less satisfying sleep amplified the positive relationship between daily mean levels and variability of positive affect (PA). The results did not differ by clinical status. The present study offers novel evidence suggesting that previous night's sleep quality influences the stability of varying daily levels of PA. Uncovering the dynamics of sleep and affect beyond mean levels will help further elucidate mechanisms linking sleep and subsequent affective experiences.

Cognitive Deficits in Aging Related to Changes in Basal Forebrain Neuronal Activity

Aging is a physiological process accompanied by a decline in cognitive performance. The cholinergic neurons of the basal forebrain provide projections to the cortex that are directly engaged in many cognitive processes in mammals. In addition, basal forebrain neurons contribute to the generation of different rhythms in the EEG along the sleep/wakefulness cycle. The aim of this review is to provide an overview of recent advances grouped around the changes in basal forebrain activity during healthy aging. Elucidating the underlying mechanisms of brain function and their decline is especially relevant in today's society as an increasingly aged population faces higher risks of developing neurodegenerative diseases such as Alzheimer's disease. The profound age-related cognitive deficits and neurodegenerative diseases associated with basal forebrain dysfunction highlight the importance of investigating the aging of this brain region.

Comparative study of quality of life 9 months post-COVID-19 infection with SARS-CoV-2 of varying degrees of severity: impact of hospitalization vs. outpatient treatment

Purpose

This experimental study was conducted during the post-COVID-19 period to investigate the relationship between the quality of life 9 months after and the severity of the SARS-CoV-2 infection in two scenarios: hospitalization (with/without medical oxygen) and outpatient treatment.

Methods

We employed the EQ-5D-5L Quality of Life tests and the PSQI as a survey to evaluate respondents' quality of life 9 months after a previous SARS-CoV-2 infection of varying severity.

Results

We identified a clear difference in the quality of life of respondents, as measured on the 100-point scale of the EQ-5D-5L test, which was significantly lower 9 months after a previous SARS-CoV-2 infection for Group 1 (n = 14), respondents who had received medical attention for SARS-CoV-2 infection in a hospital with oxygen treatment, compared to those with the SARS-CoV-2 infection who were treated without oxygen treatment (Group 2) (n = 12) and those who were treated on an outpatient basis (Group 3) (n = 13) (H = 7.08 p = 0.029). There were no intergroup differences in quality of life indicators between hospitalized patients (Group 2) and groups 1 and 3. PSQI survey results showed that "mobility," "self-care," "daily activities," "pain/discomfort," and "anxiety/ depression" did not differ significantly between the groups, indicating that these factors were not associated with the severity of the SARS-CoV-2 infection. On the contrary, the respondents demonstrated significant inter-group differences (H = 7.51 p = 0.023) and the interdependence of respiratory difficulties with the severity of clinically diagnosed SARS-CoV-2 infection. This study also demonstrated significant differences in the values of sleep duration, sleep disorders, and daytime sleepiness indicators between the three groups of respondents, which indicate the influence of the severity of the infection. The PSQI test results revealed significant differences in "bedtime" (H = 6.00 p = 0.050) and "wake-up time" (H = 11.17 p = 0.004) between Groups 1 and 3 of respondents. At 9 months after COVID-19, respondents in Group 1 went to bed at a later time (pp = 0.02727) and woke up later (p = 0.003) than the respondents in Group 3.

Conclusion

This study is the first of its kind in the current literature to report on the quality of life of respondents 9 months after being diagnosed with COVID-19 and to draw comparisons between cohorts of hospitalized patients who were treated with medical oxygen vs. the cohorts of outpatient patients. The study's findings regarding post-COVID-19 quality of life indicators and their correlation with the severity of the SARS-CoV-2 infection can be used to categorize patients for targeted post-COVID-19 rehabilitation programs.

The sleep and wake electroencephalogram over the lifespan

Both sleep and wake encephalograms (EEG) change over the lifespan. While prior studies have characterized age-related changes in the EEG, the datasets span a particular age group, or focused on sleep and wake macrostructure rather than the microstructure. Here, we present sex-stratified data from 3372 community-based or clinic-based otherwise neurologically and psychiatrically healthy participants ranging from 11 days to 80 years of age. We estimate age norms for key sleep and wake EEG parameters including absolute and relative powers in delta, theta, alpha, and sigma bands, as well as sleep spindle density, amplitude, duration, and frequency. To illustrate the potential use of the reference measures developed herein, we compare them to sleep EEG recordings from age-matched participants with Alzheimer's disease, severe sleep apnea, depression, osteoarthritis, and osteoporosis. Although the partially clinical nature of the datasets may bias the findings towards less normal and hence may underestimate pathology in practice, age-based EEG reference values enable objective screening of deviations from healthy aging among individuals with a variety of disorders that affect brain health.

Factors Affecting Depression and Its Relation to Sleep Quality among Parents of Type 1 Diabetes Patients

This study investigated factors affecting depression (CES-D) among parents of patients with type-1 diabetes mellitus (T1DM), a chronic disease that requires constant management. A complex set of factors influence depression in parents and thus requires further research. This is a cross-sectional descriptive study. A survey on related variables was conducted on 217 parents of patients with T1DM. The collected data were analyzed using the PASW Statistics program, and factors influencing participants’ depression were identified through stepwise multiple regression. The results show that three variables exerted a significant effect on depression (source of information, resilience–personal competence, and Pittsburgh sleep quality index score), and all the variables explained a majority of the variance in depression. The results indicate that the parents of patients with T1DM were less depressed when the source of information was personal, when their resilience–personal competence was high, and when their Pittsburgh sleep quality index (PSQI) score was low. Interventions targeting parents of patients with T1DM should be performed with positive information on how to overcome diabetes in their children, increase resilience–personal competence, and increase sleep quality.

Novel methods for elucidating modality importance in multimodal electrophysiology classifiers

Introduction

Multimodal classification is increasingly common in electrophysiology studies. Many studies use deep learning classifiers with raw time-series data, which makes explainability difficult, and has resulted in relatively few studies applying explainability methods. This is concerning because explainability is vital to the development and implementation of clinical classifiers. As such, new multimodal explainability methods are needed.

Methods

In this study, we train a convolutional neural network for automated sleep stage classification with electroencephalogram (EEG), electrooculogram, and electromyogram data. We then present a global explainability approach that is uniquely adapted for electrophysiology analysis and compare it to an existing approach. We present the first two local multimodal explainability approaches. We look for subject-level differences in the local explanations that are obscured by global methods and look for relationships between the explanations and clinical and demographic variables in a novel analysis.

Results

We find a high level of agreement between methods. We find that EEG is globally the most important modality for most sleep stages and that subject-level differences in importance arise in local explanations that are not captured in global explanations. We further show that sex, followed by medication and age, had significant effects upon the patterns learned by the classifier.

Discussion

Our novel methods enhance explainability for the growing field of multimodal electrophysiology classification, provide avenues for the advancement of personalized medicine, yield unique insights into the effects of demographic and clinical variables upon classifiers, and help pave the way for the implementation of multimodal electrophysiology clinical classifiers.

Relationships Between Remote Learning Modalities and Nursing Students' Perceptions of Their Sleep Quality During the COVID-19 Pandemic

BACKGROUND

The relationship between learning modalities and nursing students' sleep quality during the coronavirus disease (COVID-19) pandemic is unknown.

PURPOSE

This study examined the relationships between remote learning and the sleep quality of nursing students during the COVID-19 pandemic.

METHODS

Using a cross-sectional descriptive design, 890 nursing students were surveyed online to identify sleeping habits and learning modalities.

RESULTS

There were no significant correlations between remote learning hours, self-reported sleep hours, and sleep quality. The asynchronous-only group reported better sleep quality than the in-person and online hybrid group after controlling for health conditions and grade point average. Students who reported that remote learning had impacted their sleep had poorer sleep quality.

CONCLUSIONS

This study provides insight into how different learning modalities impact nursing students' sleep quality during the pandemic.

To sleep or not to sleep - Effects on memory in normal aging and disease

Sleep behavior undergoes significant changes across the lifespan, and aging is associated with marked alterations in sleep amounts and quality. The primary sleep changes in healthy older adults include a shift in sleep timing, reduced slow-wave sleep, and impaired sleep maintenance. However, neurodegenerative and psychiatric disorders are more common among the elderly, which further worsen their sleep health. Irrespective of the cause, insufficient sleep adversely affects various bodily functions including energy metabolism, mood, and cognition. In this review, we will focus on the cognitive changes associated with inadequate sleep during normal aging and the underlying neural mechanisms.

Subjective and objective sleep quality does not predict behavioural episodic foresight in younger or older adults

Episodic foresight refers to one's capacity to use imagined scenarios to guide future-directed behaviors. It is important in facilitating complex activities of daily living, such as managing finances. Broader literature shows that older adults perform more poorly on tests of episodic foresight relative to their younger counterparts. At the same time, age-related changes in sleep often contribute to age-related decline in other cognitive abilities known to support episodic foresight, such as memory. No study to date has tested whether sleep quality is associated with episodic foresight when it is measured behaviorally; or whether this relationship is moderated by age. To address this, in the present study healthy younger (n = 39) and older (n = 41) adults were asked to wear an actigraphy watch and self-report their sleep quality for seven nights. Participants then completed the virtual-week foresight task-a behavioral assessment of episodic foresight. Neither objective or subjective sleep quality predicted episodic foresight outcomes, and this was not moderated by age group. Bayesian analyses provided evidence in favour of the null hypotheses. These results suggest that sleep quality (at least in healthy adult populations) may not be linked to episodic foresight.

Associated factors with depression and sleep quality in T1DM patients: a cross-sectional descriptive study

BACKGROUND

Individuals with type 1 diabetes (T1DM) may experience sleep problems, usually due to low blood sugar levels during sleep or performance of blood sugar management (e.g., blood sugar monitoring). This study aimed to identify the disease-related characteristics, psychosocial aspects, and related factors underlying sleep quality in patients with T1DM.

METHODS

This study employed a descriptive research design. The participants were 159 individuals with T1DM who completed online questionnaires. The data were analyzed using descriptive statistics, correlations, and multiple regression analyses.

RESULTS

The average score for depression in T1DM patients was 23.77 (SD 5.31), and sleep quality received a score of 4.58 (SD 3.22). Depression was positively correlated with sleep quality and negatively correlated with the total resilience score. The factors linked to depression in T1DM patients were duration of disease, sleep latency, sleep duration, sleep disturbance, and resilience-acceptance of self and life sub-factors, with an explanatory power of 44.4% for the depression variance. The associated factors with sleep quality in T1DM patients were complications, resilience-personal competence sub-factors, and depression, with an explanatory power of 37.4% for sleep quality variance.

CONCLUSIONS

The results of this study suggest that to improve sleep quality in patients with T1DM, it is necessary to develop and support disease management to prevent complications and implement interventions for improving resilience and reducing negative emotions such as depression.

An emerging role of astrocytes in aging/neuroinflammation and gut-brain axis with consequences on sleep and sleep disorders

Understanding the role of astrocytes in the central nervous system has changed dramatically over the last decade. The accumulating findings indicate that glial cells are involved not only in the maintenance of metabolic and ionic homeostasis and in the implementation of trophic functions but also in cognitive functions and information processing in the brain. Currently, there are some controversies regarding the role of astrocytes in complex processes such as aging of the nervous system and the pathogenesis of age-related neurodegenerative diseases. Many findings confirm the important functional role of astrocytes in age-related brain changes, including sleep disturbance and the development of neurodegenerative diseases and particularly Alzheimer's disease. Until recent years, neurobiological research has focused mainly on neuron-glial interactions, in which individual astrocytes locally modulate neuronal activity and communication between neurons. The review considers the role of astrocytes in the physiology of sleep and as an important "player" in the development of neurodegenerative diseases. In addition, the features of the astrocytic network reorganization during aging are discussed.

Short sleep duration is associated with a wide variety of medical conditions among United States military service members

OBJECTIVES

This cross-sectional study investigated self-reported sleep duration and its association with a comprehensive range of clinically-diagnosed medical condition categories (CDMCs), as well as the relationship between short sleep duration (≤6 h) and demographic/lifestyle factors, among United States military service members (SMs).

METHODS

A stratified random sample of SMs (n = 20,819) completed an online questionnaire on usual daily hours of sleep and demographic/lifestyle characteristics. CDMCs for a six-month period prior to questionnaire completion were obtained from a comprehensive military electronic medical surveillance system and grouped into 33 CDMCs covering both broad and specific medical conditions. Prevalence of CDMCs was compared among three sleep duration categories (≤4, 5-6 and ≥7 h).

RESULTS

SMs reported a mean ± standard deviation of 6.3 ± 1.4 h of sleep per day. After adjustment for demographic/lifestyle characteristics, shorter sleep duration was associated with higher odds of a medical condition in 25 of 33 CDMCs, with most (n = 20) demonstrating a dose-response relationship. The five CDMCs with the largest differences between ≤4 vs ≥ 7 h sleep were: diseases of the nervous system (odds ratio [OR] = 2.9, 95% confidence interval [95%CI] = 2.4-3.4), mental/behavioral diseases (OR = 2.7, 95%CI = 2.3-3.2), diseases of the musculoskeletal system (OR = 1.9, 95%CI = 1.6-2.1), diseases of the circulatory system (OR = 1.7, 95%CI = 1.3-2.2), and diseases of the digestive system (OR = 1.6, 95%CI = 1.2-2.0). Six hours of sleep or less was independently associated with older age, less formal education, race, Hispanic ethnicity, higher body mass index, smoking, and military service branch.

CONCLUSIONS

In this young, physically active population, reporting shorter sleep duration was associated with a higher risk of multiple CDMCs.

Sleep spindles in people with schizophrenia, schizoaffective disorders or bipolar disorders: a pilot study in a general population-based cohort

BACKGROUND

Sleep spindles have been involved in sleep stabilization and sleep-related memory mechanisms and their deficit emerged as possible biomarker in schizophrenia. However, whether this sleep phenotype is also present in other disorders that share psychotic symptoms remains unclear. To address this gap, we assessed sleep spindles in participants of a prospective population-based cohort who underwent psychiatric assessment (CoLaus|PsyCoLaus) and polysomnographic recording (HypnoLaus).

METHODS

Sleep was recorded using ambulatory polysomnography in participants (N = 1037) to the PsyCoLaus study. Sleep spindle parameters were measured in people with a lifelong diagnosis of schizophrenia (SZ), schizoaffective depressive (SAD), schizoaffective manic (SAM), bipolar disorder type I (BP-I) and type II (BP-II). The associations between lifetime diagnostic status (independent variables, SZ, SAD, SAM, BPD-I, BPD-II, controls) and spindle parameters (dependent variables) including density, duration, frequency and maximum amplitude, for all (slow and fast), slow- and fast-spindle were assessed using linear mixed models. Pairwise comparisons of the different spindle parameters between the SZ group and each of the other psychiatric groups was performed using a contrast testing framework from our multiple linear mixed models.

RESULTS

Our results showed a deficit in the density and duration of sleep spindles in people with SZ. They also indicated that participants with a diagnosis of SAD, SAM, BP-I and BP-II exhibited different sleep spindle phenotypes. Interestingly, spindle densities and frequencies were different in people with a history of manic symptoms (SAM, BP-I, and BP-II) from those without (SZ, SAD).

CONCLUSIONS

Although carried out on a very small number of participants due to the low prevalence of these disorders in general population, this pilot study brought new elements that argued in favor of a deficit of sleep spindles density and duration in people with schizophrenia. In addition, while we could expect a gradual change in intensity of the same sleep spindle parameters through psychotic diagnoses, our results seem to indicate a more complex situation in which the frequency of sleep spindles might be more impacted by diagnoses including a history of mania or hypomania. Further studies with a larger number of participants are required to confirm these effects.

Sleep profile status based on substance use, lipids and demographic variables in Tabari cohort study

BACKGROUND

This study aims to investigate the situation of sleep profile and its related factors in the Tabari Cohort Tabari (TCS) population.

METHODS

The information of 10255 of the Tabari cohort population in the enrolment phase was used in this study. The sleep profile data was collected and recorded by trained questioners. The sleep duration in day & night, the time interval between going bed and falling asleep, continuous use of sedatives, involuntary nap, limb hypermobility during sleep and shift working were determined for each person. Data analysis was performed by independent T test and Pearson correlation coefficient.

RESULTS

Mean, standard deviation, median, minimum and maximum of sleep duration in this population were 7.6, 1.6, 7.5, 0.5 and 17 h. Frequency of sleeping less than 6 h, 6-10 h and more than 10 h were 1168(11.4%), 8463(82.5%) and 624(6.1%) respectively. Prevalence of sleeping more than 10 h among men and women were 5% and 6.8% respectively (P < 0.001). Prevalence of sedative routine use among men and women were 4.7% and 9.6% respectively (P < 0.001). There were significant relationships between sleep duration and area residence, age group (P < 0.001), education level (P < 0.001), socioeconomic level (P < 0.001), triglyceride (P = 0.002), HDL-cholesterol (P = 0.013) and Cholesterol total (P = 0.021). There was a negative correlation between age and sleep duration (r = -0.062, P < 0.001).

CONCLUSION

The results showed the association of the quality and quantity of sleep with personal, social, environmental and biological factors such as gender, age, economic status, educational status, and lipid profile. Therefore without proper intervention, the incidence of outcomes associated with these risk factors can be predicted in TCS In later years.

Perceived risk of COVID-19 exposure and poor COVID-19 prognosis impair sleep: The mediating and moderating roles of COVID-19-related anxiety and knowledge

The ongoing COVID‐19 pandemic has been linked to increased levels of stress, depression, and anxiety in many people around the world. Therefore, identifying individuals at risk of psychosocial burden during this unprecedented crisis is essential for developing prevention measures and treatment options for mental health issues. To this aim, we investigated two risk groups: individuals at higher risk of exposure to the virus and individuals at higher risk of poor prognosis if they contract the virus. We conducted a survey (N = 4167) with a representative sample of the German population and assessed perceived risk of COVID‐19 exposure and poor prognosis if infected, COVID‐19‐related anxiety, problems with sleep and daytime functioning, as well as self‐reported knowledge about the disease. Results showed that perceived risk group membership was linked to increased problems with sleep and daytime functioning via elevated levels of COVID‐19‐related anxiety. This mediated effect was further moderated by self‐reported COVID‐19 knowledge, but only for individuals who rated themselves at higher risk of COVID‐19 exposure. Thus, knowledge buffered the negative effect of exposure risk on anxiety and ultimately on sleep in this risk group. Reaching individuals at increased risk of exposure with clear information about the disease, how to prevent infection, and treatment options could be an effective strategy to contain anxiety levels and promote good sleep, which is important for general well‐being.

Sleep during travel balances individual sleep needs

Travel is expected to have a deleterious effect on sleep, but an epidemiological-scale understanding of sleep changes associated with travel has been limited by a lack of large-scale data. Our global dataset of ~20,000 individuals and 3.17 million nights (~218,000 travel nights), while focused mainly on short, non-time-zone-crossing trips, reveals that travel has a balancing effect on sleep. Underslept individuals typically sleep more during travel than when at home, while individuals who average more than 7.5 hours of sleep at home typically sleep less when travelling. The difference in travel sleep quantity depends linearly on home sleep quantity and decreases as median sleep duration increases. On average, travel wake time advances to later hours on weekdays but earlier hours on weekends. Our study emphasizes the potential for consumer-grade wearable device data to explore how environment and behaviour affect sleep.

Positive rumination can (also) interfere with sleep: A study in a non-clinical sample

It is postulated that negative ruminations perpetuate insomnia symptoms by increasing arousal. Less is known about the role of positive rumination. In this study, we set out to test the association between positive and negative ruminations and insomnia symptoms in a non-clinical sample, asking whether reappraisal and suppression moderate the relationship between rumination types and symptoms of insomnia.

METHODS

A convenience sample of 354 participants (59% women), ages 18-50, responded to online questionnaires regarding symptoms of insomnia (Insomnia Severity Index [ISI]), Emotion Regulation Questionnaire that provides separate scales for Reappraisal and Suppression, Negative Rumination (Ruminative Response Scale), Positive Rumination and Dampening (Responses to Positive Affect questionnaire), and general health and demographics.

RESULTS

About 30% of respondents had moderate to severe symptoms of insomnia according to the ISI. The primary hypothesis was tested using three moderation models, where rumination type, emotion regulation styles, and interaction terms were predictors, and ISI scores were the outcome variable. Negative rumination positively predicted ISI (β = 0.56, p < 0.001), while the interaction terms with Reappraisal (β = 0.02, p = 0.575) and Suppression (β = 0.07, p = 0.092) were not significant. Dampening also positively predicted ISI (β = 0.56, p < 0.001), with the interaction term with Reappraisal nearly significant (β = -0.09, p = 0.060), but not with Suppression (β = 0.08, p =0.098). Positive rumination negatively predicted ISI (β = -0.12, p = 0.021), this relationship was reversed with emotion regulation factors in the model (β = 0.11, p = 0.094), where the interaction with Reappraisal (β = 0.13, p = 0.020) and Suppression (β = -0.13, p = 0.024) were both significant.

DISCUSSION

Positive Rumination weakly and negatively correlated with ISI, but the combination with Reappraisal was associated with more insomnia symptoms. By contrast, Dampening was associated with more insomnia symptoms, with minimal to no moderating effects. These observations are interpreted in the context of the role of emotion regulation strategies and sleep, and their potential clinical implications.

Is unemployment associated with inefficient sleep habits? A cohort study using objective sleep measurements

Unemployed people could be at risk of developing inefficient sleep habits by spending excessive time in bed, as they lack a structuring activity. This could impact their mental health and reintegration into labour. This study aims to analyse possible associations between employment status and sleep parameters using actigraphy. Subjects (148 employed and 50 unemployed) were drawn from a German population-based cohort. Sleep parameters were measured with the SenseWear Bodymedia Pro 3 armband. Comparison of means concerning sleep duration, sleep efficiency, time of sleep and sleep fragmentation was performed separately for week days and weekends. Multiple linear regression analysis was performed to analyse group differences controlling for covariates. Finally, we defined cut-off scores for each sleep variable, and analysed the distribution of subjects above and below these values. Unemployed people did not sleep significantly longer than employed people. However, on week days, they displayed night sleep efficiency reduced by on average > 5% points, they lay down for 28 min longer, had later mid sleep time (38 min) and sleep offset (55 min), as well as more frequent awakenings after sleep onset accounting for being awake 28 min longer (all p ≤ 0.005). Sleep in unemployed subjects compared with employed subjects aged 41-64 years was less efficient, more fragmented and shifted to a later point of the night. Results support prior findings that unemployment has a negative influence on sleep quality. Unemployed individuals could benefit from intervention programmes aiming at the adoption of healthier sleep habits.

EEG sleep macrostructure and sleep spindles in early infancy

Study Objectives

Sleep features in infancy are potential biomarkers for brain maturation but poorly characterized. We describe normative values for sleep macrostructure and sleep spindles at 4–5 months of age.

Methods

Healthy term infants were recruited at birth and had daytime sleep electroencephalograms (EEGs) at 4–5 months. Sleep staging was performed and five features were analyzed. Sleep spindles were annotated and seven quantitative features were extracted. Features were analyzed across sex, recording time (am/pm), infant age, and from first to second sleep cycles.

Results

We analyzed sleep recordings from 91 infants, 41% females. Median (interquartile range [IQR]) macrostructure results: sleep duration 49.0 (37.8–72.0) min (n = 77); first sleep cycle duration 42.8 (37.0–51.4) min; rapid eye movement (REM) percentage 17.4 (9.5–27.7)% (n = 68); latency to REM 36.0 (30.5–41.1) min (n = 66). First cycle median (IQR) values for spindle features: number 241.0 (193.0–286.5), density 6.6 (5.7–8.0) spindles/min (n = 77); mean frequency 13.0 (12.8–13.3) Hz, mean duration 2.9 (2.6–3.6) s, spectral power 7.8 (4.7–11.4) µV², brain symmetry index 0.20 (0.16–0.29), synchrony 59.5 (53.2–63.8)% (n = 91). In males, spindle spectral power (µV²) was 24.5% lower (p = .032) and brain symmetry index 24.2% higher than females (p = .011) when controlling for gestational and postnatal age and timing of the nap. We found no other significant associations between studied sleep features and sex, recording time (am/pm), or age. Spectral power decreased (p < .001) on the second cycle.

Conclusion

This normative data may be useful for comparison with future studies of sleep dysfunction and atypical neurodevelopment in infancy.

Clinical Trial Registration: BABY SMART (Study of Massage Therapy, Sleep And neurodevelopMenT) (BabySMART)

URL: https://clinicaltrials.gov/ct2/show/results/NCT03381027?view=results.

ClinicalTrials.gov Identifier: NCT03381027

Overweight and Obesity are Potential Risk Factors for Disrupted Nocturnal Sleep in Iranian Adults: A Cross-Sectional Study

Objectives: Obesity is a risk factor for several chronic conditions, including sleep disorders. We aimed to analyze the relationship between BMI, body fat percentage (FAT%), hip and waist circumference, and weight on the duration of nocturnal sleep. Methods: This study was part of the MASHAD cohort study. In all participants BMI and FAT% were measured. BMI was used to categorize individuals as obese, overweight, and normal subjects. FAT% was used to categorize individuals into tertile: tertile 1 (low) < 27.5, tertile 2 (medium) 27.5-41, and tertile 3 (high) > 41. The level of nightly sleep duration was categorized into three groups: <6, 6-8 (reference group), and >8 h. Results: There was a significant inverse association between body weight and duration of sleep (p < 0.05). Obese and overweight participants had 1.152 OR (CI:1.083-1.225) and 1.126 OR (CI:1.063-1.194) for a short duration of nocturnal sleep, respectively, relative to those with a normal BMI. Conclusion: BMI was an independent determinant of nocturnal sleep duration; obesity and overweight may have negative consequences on sleep duration. Weight control should be considered as a factor in adjusting sleep quality.

The relationship between sleep quality and quality of life in aging: a systematic review and meta-analysis

This study examined the available literature concerning the association between sleep quality and quality of life (QoL) in autonomous older people with no sleep disorders. A systematic review and meta-analysis were conducted on studies identified in the PsycInfo, PubMed and Scopus databases that examined the associations between QoL and sleep quality in older adults. Our systematic literature search identified 23 studies concerning a total of 21,092 participants (range of mean ages: 58-79 years). The results showed that self-reported sleep quality, but not objective sleep quality, correlated positively with QoL with a moderate effect size (for self-reported sleep quality, the overall estimate of the average effect size was a Pearson's r = .28 [95% CI: .34, .23]; for objective sleep quality, it was r = .01 [.12, -.09]). This also applied to the main domains of QoL concerning physical and psychological health, social relationships and environmental aspects (the estimated average effect sizes ranged from Pearson's r = .13 to r = .35). These findings highlight the influence of sleep quality, and particularly of self-reported sleep quality, on QoL (as a whole and in its specific domains) in older adults with normal aging and no insomnia. This influence should therefore be investigated systematically when examining QoL.

Reduced Insulin-Like Growth Factor-I Effects in the Basal Forebrain of Aging Mouse

It is known that aging is frequently accompanied by a decline in cognition. Furthermore, aging is associated with lower serum IGF-I levels that may contribute to this deterioration. We studied the effect of IGF-I in neurons of the horizontal diagonal band of Broca (HDB) of young (≤6 months old) and old (≥20-month-old) mice to determine if changes in the response of these neurons to IGF-I occur along with aging. Local injection of IGF-I in the HDB nucleus increased their neuronal activity and induced fast oscillatory activity in the electrocorticogram (ECoG). Furthermore, IGF-I facilitated tactile responses in the primary somatosensory cortex elicited by air-puffs delivered in the whiskers. These excitatory effects decreased in old mice. Immunohistochemistry showed that cholinergic HDB neurons express IGF-I receptors and that IGF-I injection increased the expression of c-fos in young, but not in old animals. IGF-I increased the activity of optogenetically-identified cholinergic neurons in young animals, suggesting that most of the IGF-I-induced excitatory effects were mediated by activation of these neurons. Effects of aging were partially ameliorated by chronic IGF-I treatment in old mice. The present findings suggest that reduced IGF-I activity in old animals participates in age-associated changes in cortical activity.

Location, Spreading and Oral Corticosteroids are Associated with Insomnia in Vitiligo Patients: A Case-Control Study

Background

Vitiligo can cause disfiguration, impair the social function of the patients and induce physiological burdens. However, limited research about the health-related quality of life has been conducted in vitiligo patients’ sleeping conditions.

Objective

To evaluate the prevalence, severity, and risk factors of insomnia in vitiligo patients.

Methods

This case–control study was performed in March 2021. An online survey questionnaire including baseline information and the sleep-related instrument was sent to 762 vitiligo patients. The vitiligo-related evaluation was conducted by online video interview. According to whether having insomnia or not, patients were grouped and compared their clinical and demographic characteristics. The logistic regression model was conducted to analyze the risk factors for insomnia.

Results

A total of 409 patients were included. About 49.9% of patients (204/409) experienced insomnia. About 55.9% (114/204) of the insomnia in vitiligo patients was adjustment sleep disorder caused by vitiligo. Development, aggravation, or recurrence of vitiligo were deemed as the first reason for insomnia in 71.1% of the sample (81/114). There were significant differences in age (32.1±4.1 vs 27.9±4.2 years, P < 0.001), the percentage of female (62.8% vs 49.3%, P=0.006) and working in the urban areas (77.0% vs 66.3%, P = 0.017), vitiligo in face and neck (67.2% vs 48.8%, P < 0.001), progression in vitiligo (65.7% vs 49.3%, P=0.001), oral corticosteroids (25.0% vs 16.6%, P=0.036) and depression (5.4% vs 0.5%, P = 0.003) between groups. After adjusting for gender, age and comorbidity, the multivariate logistic regression revealed that vitiligo in face and neck (OR=2.62; P=0.032), progression in vitiligo (OR=2.50; P=0.002), and oral corticosteroids (OR=2.71; P=0.021) remained risk factors for insomnia in vitiligo patients.

Conclusion

Insomnia is prevalent in vitiligo patients. Dermatologists should identify this condition carefully, especially humanistic factors in social life, and perform individualized “non-drug” treatment.

Sleep in Normal Aging, Homeostatic and Circadian Regulation and Vulnerability to Sleep Deprivation

In the context of geriatric research, a growing body of evidence links normal age-related changes in sleep with many adverse health outcomes, especially a decline in cognition in older adults. The most important sleep alterations that continue to worsen after 60 years involve sleep timing, (especially early wake time, phase advance), sleep maintenance (continuity of sleep interrupted by numerous awakenings) and reduced amount of sigma activity (during non-rapid eye movement (NREM) sleep) associated with modifications of sleep spindle characteristics (density, amplitude, frequency) and spindle-Slow Wave coupling. After 60 years, there is a very clear gender-dependent deterioration in sleep. Even if there are degradations of sleep after 60 years, daytime wake level and especially daytime sleepiness is not modified with age. On the other hand, under sleep deprivation condition, older adults show smaller cognitive impairments than younger adults, suggesting an age-related lower vulnerability to extended wakefulness. These sleep and cognitive age-related modifications would be due to a reduced homeostatic drive and consequently a reduced sleep need, an attenuation of circadian drive (reduction of sleep forbidden zone in late afternoon and wake forbidden zone in early morning), a modification of the interaction of the circadian and homeostatic processes and/or an alteration of subcortical structures involved in generation of circadian and homeostatic drive, or connections to the cerebral cortex with age. The modifications and interactions of these two processes with age are still uncertain, and still require further investigation. The understanding of the respective contribution of circadian and homeostatic processes in the regulation of neurobehavioral function with aging present a challenge for improving health, management of cognitive decline and potential early chronobiological or sleep-wake interventions.

Single-channel EEG classification of sleep stages based on REM microstructure

Rapid-eye movement (REM) sleep, or paradoxical sleep, accounts for 20-25% of total night-time sleep in healthy adults and may be related, in pathological cases, to parasomnias. A large percentage of Parkinson's disease patients suffer from sleep disorders, including REM sleep behaviour disorder and hypokinesia; monitoring their sleep cycle and related activities would help to improve their quality of life. There is a need to accurately classify REM and the other stages of sleep in order to properly identify and monitor parasomnias. This study proposes a method for the identification of REM sleep from raw single-channel electroencephalogram data, employing novel features based on REM microstructures. Sleep stage classification was performed by means of random forest (RF) classifier, K-nearest neighbour (K-NN) classifier and random Under sampling boosted trees (RUSBoost); the classifiers were trained using a set of published and novel features. REM detection accuracy ranges from 89% to 92.7%, and the classifiers achieved a F-1 score (REM class) of about 0.83 (RF), 0.80 (K-NN), and 0.70 (RUSBoost). These methods provide encouraging outcomes in automatic sleep scoring and REM detection based on raw single-channel electroencephalogram, assessing the feasibility of a home sleep monitoring device with fewer channels.

Sleep, Cognition, and Yoga

Stress is one of the major problems globally, associated with poor sleep quality and cognitive dysfunction. Modern society is plagued by sleep disturbances, either due to professional demands or lifestyle or both the aspects, often leading to reduced alertness and compromised mental function, besides the well documented ill effects of disturbed sleep on physiological functions. This pertinent issue needs to be addressed. Yoga is an ancient Indian science, philosophy and way of life. Recently, yoga practice has become increasingly popular worldwide. Yoga practice is an adjunct effective for stress, sleep and associated disorders. There are limited well controlled published studies conducted in this area. We reviewed the available literature including the effect of modern lifestyle in children, adolescents, adults and geriatric population. The role of yoga and meditation in optimizing sleep architecture and cognitive functions leading to optimal brain functioning in normal and diseased state is discussed. We included articles published in English with no fixed time duration for literature search. Literature was searched mainly by using PubMed and Science Direct search engines and critically examined. Studies have revealed positive effects of yoga on sleep and cognitive skills among healthy adults as well as patients of some neurological diseases. Further, on evaluating the published studies, it is concluded that sleep and cognitive functions are optimized by yoga practice, which brings about changes in autonomic function, structural changes, changes in metabolism, neurochemistry and improved functional brain network connectivity in key regions of the brain.

Associations of Dietary ω-3, ω-6 Fatty Acids Consumption with Sleep Disorders and Sleep Duration among Adults

The relationship between ω-3 and ω-6 fatty acids consumption and sleep disorders or duration are controversial. Therefore, we used the data of the National Health and Nutrition Examination Survey 2007-2016 in this cross-sectional study to explore their relationships. ω-3 and ω-6 fatty acids consumption was assessed using two 24 h dietary recall interviews. Sleep disorders and sleep duration were based on self-reported data. Logistic regression models and restricted cubic spline analyses were used. Compared with tertile one, the odds ratios (ORs) and 95% confidence intervals (CIs) of sleep disorders for the second tertile of ω-6 fatty acid intake and the highest tertile of ω-6:ω-3 ratio were 1.30 (1.04-1.62) and 1.36 (1.08-1.70), respectively. Inverse U-shaped and linear dose-response relationships were observed between dietary ω-6 fatty acid intake and ω-6:ω-3 ratio and sleep disorders, respectively. In addition, ω-3 fatty acid consumption was adversely related to sleep disorders in men and the OR (95% CI) was 0.68 (0.49-0.95). Compared with normal sleep duration, ω-3 fatty acid consumption was negatively related to very short, short, and long sleep duration risk. The relative risk ratios (RRRs) were 0.53 (0.35-0.81), 0.79 (0.67-0.93), and 0.81 (068-0.98), respectively. The RRR of very short sleep for ω-6 fatty acid consumption was 0.57 (0.45-0.73). Our study indicates that ω-6 fatty acid consumption and the ω-6:ω-3 ratio are positively associated with the risk of sleep disorders, while the negative association between ω-3 fatty acids and sleep disorders may exist only in men. Furthermore, ω-3 and ω-6 fatty acid consumption are negatively related to the risk of non-normal sleep duration.

Gender differences in nighttime sleep patterns and variability across the adult lifespan: a global-scale wearables study

STUDY OBJECTIVES

Previous research on sleep patterns across the lifespan have largely been limited to self-report measures and constrained to certain geographic regions. Using a global sleep dataset of in situ observations from wearable activity trackers, we examine how sleep duration, timing, misalignment, and variability develop with age and vary by gender and BMI for nonshift workers.

METHODS

We analyze 11.14 million nights from 69,650 adult nonshift workers aged 19-67 from 47 countries. We use mixed effects models to examine age-related trends in naturalistic sleep patterns and assess gender and BMI differences in these trends while controlling for user and country-level variation.

RESULTS

Our results confirm that sleep duration decreases, the prevalence of nighttime awakenings increases, while sleep onset and offset advance to become earlier with age. Although men tend to sleep less than women across the lifespan, nighttime awakenings are more prevalent for women, with the greatest disparity found from early to middle adulthood, a life stage associated with child-rearing. Sleep onset and duration variability are nearly fixed across the lifespan with higher values on weekends than weekdays. Sleep offset variability declines relatively rapidly through early adulthood until age 35-39, then plateaus on weekdays, but continues to decrease on weekends. The weekend-weekday contrast in sleep patterns changes as people age with small to negligible differences between genders.

CONCLUSIONS

A massive dataset generated by pervasive consumer wearable devices confirms age-related changes in sleep and affirms that there are both persistent and life-stage dependent differences in sleep patterns between genders.