Sleep regularity is a stronger predictor of mortality risk than sleep duration: A prospective cohort study

Wakefulness after sleep offset and the elevated risk of mortality in older adults with evening preferences: A community-based 5-year longitudinal study

BACKGROUND AND OBJECTIVES

This study investigated the relationship between wakefulness after sleep offset timing (WASF), evening chronotype preferences, and mortality risk in community-dwelling older adults.

RESEARCH DESIGN AND METHODS

We conducted a community-based longitudinal study with a sample of 4167 older adults aged ≥60. The sleep characteristics, WASF, subjective chronotype preferences, and other relevant variables of the participants at baseline were evaluated. We examined the association between WASF and mortality over a 5-year period using Cox proportional hazards models, with stratification by subjective chronotype preferences to explore potential effect modification.

RESULTS

Data from 3734 participants were analyzed (71.1 ± 6.9 years; 2114 [56.6 %] women). The 5-year mortality incidence was 6.3 %. Overall, participants had a median (IQR) of 5.0 (2-20) min WASF, and 767 (20.6 %) were evening types. WASF of ≤5 min = 10.6 (95 % CI, 8.9-12.8), WASF of >5 min = 14.6 (95 % CI, 12.1-17.6). The mortality incidence rates per 1000 person-years were: WASF of ≤5 min = 10.6 (95 % CI, 8.9-12.8) and WASF of >5 min = 14.6 (95 % CI, 12.1-17.6). Even after adjusting for covariates, the longer WASF participants had a higher hazard ratio of 1.40 (95 % CI, 1.04-1.88) compared to the shorter WASF participants. Regular, prolonged WASF was found to be significantly associated with an increased risk of mortality among evening-type individuals (2.69; 95 % CI: 1.19-6.08) in the stratified model based on subjective chronotype preferences. However, we found no statistically significant association among the other types.

DISCUSSION AND IMPLICATIONS

Reducing morning time in bed, and addressing prolonged WASF are crucial factors in decreasing mortality risk among older adults, especially among those with evening preferences.

Nonpsychiatric Comorbidities in Pediatric Restless Leg Syndrome

Many medical disorders coexist with restless leg syndrome (RLS) and frequently have a bidirectional relationship. Specific examination of these relationships can help in more timely identification and intervention of RLS, as well as more comprehensive care delivery of the various related morbidities resulting in improved health outcomes, sleep, and quality of life. RLS in the pediatric population can be difficult to identify and frequently can be missed or mischaracterized as normal growth-related features. The goal is to enhance recognition of RLS, periodic limb movement disorder, and their medical comorbidities in a compressed time frame and launch a personalized treatment approach.

The role of the DSM-5 maladaptive personality traits in adherence to sleep hygiene behaviors and sleep duration

Recent research explores the associations between maladaptive personality constructs proposed by the DSM-5 Alternative Model of Personality Disorders (AMPD) and general psychopathology whereas research on sleep hygiene behaviors and sleep duration is poor. This study first aimed to classify an adult population based on bedtime, mobile phone use before bedtime, and sleep duration. The second aim was to compare the AMPD trait domains including negative affectivity, detachment, antagonism, disinhibition, and psychoticism across the derived clusters. The cross-sectional study consisted of 481 college students from the west of Iran (mean age of 27.7 ± 6.8 years; 69.4% female). Several single items plus the Brief Form of Personality Inventory for DSM-5 were used for data collection. A hierarchical cluster analysis was performed to determine latent categories, and the AMPD domain scores between the clusters were compared using multivariate analysis of variance and post hoc tests. The cluster analysis identified three categories containing a vulnerable group (poor sleep hygiene behaviors but sufficient sleep duration), an unhealthy group (poor sleep hygiene behaviors plus insufficient sleep duration), and a healthy group (good sleep hygiene behaviors plus sufficient sleep duration). The results showed that the clusters significantly differed in all trait domains (except for detachment) and the total average score with higher mean scores, especially for the unhealthy cluster. Our findings highlight the meaningful impact of maladaptive personality traits on unhealthy sleep hygiene behaviors and insufficient sleep. Preventive medicine can identify at-risk populations by screening for maladaptive personality in early adulthood.

A narrative review of sleep and breast cancer: from epidemiology to mechanisms

Breast cancer is the leading cause of cancer-related death and the most common cancer among women worldwide. It is crucial to identify potentially modifiable risk factors to intervene and prevent breast cancer effectively. Sleep factors have emerged as a potentially novel risk factor for female breast cancer. Current epidemiologic studies suggest a significant impact of sleep factors on breast cancer. Exposure to abnormal sleep duration, poor sleep quality, sleep disorders, sleep medication use, or night shift work can increase the risk of breast cancer by decreasing melatonin secretion, disrupting circadian rhythm, compromising immune function, or altering hormone levels. However, there are still controversies regarding the epidemiologic association, and the underlying mechanisms have yet to be fully elucidated. This paper summarizes the epidemiologic evidence on the associations between sleep factors, including sleep duration, sleep quality, sleep disorders, sleep medication use, sleep habits, and night shift work, and the development of breast cancer. The potential mechanisms underlying these associations were also reviewed.

Association Between Depression and the Short Sleep Duration on Weekdays and Weekends in South Korean Adults: A Cross-Sectional Study Using the 2016 and 2018 Korea National Health and Nutrition Examination Survey

OBJECTIVE

This study aimed to examine the association between sleep duration on weekdays and weekends and depression among Korean adults.

DESIGN

Cross-sectional study.

SETTING

South Korea, utilizing data from 2016 and 2018 Korea National Health and Nutrition Examination Survey (KNHANES).

PARTICIPANTS

A total of 7669 South Korean adults aged 19-64 years.

MEASURES

Depression was assessed using the Patient Health Questionnaire-9 (PHQ-9). Sleep duration was classified separately for weekdays and weekends and categorized into three groups: <7, 7-9, and ≥9 h. Multiple logistic regression analysis was performed, adjusting for socioeconomic, lifestyle, and health-related variables.

RESULTS

Among the participants, 3.6% were identified as having depression. On weekdays, 40.5% of respondents reported an average sleep duration of less than 7 h per day, whereas only 20.3% did so on weekends. Compared to those who averaged 7 to less than 9 h of sleep per day, individuals with short sleep duration (<7 h) on weekdays had significantly higher odds of depression (OR: 1.65; 95% CI: 1.16-2.35), as did those with short sleep on weekends (OR: 1.62; 95% CI: 1.10-2.38). Notably, participants who consistently averaged less than 7 h of sleep per day across both weekdays and weekends demonstrated the highest odds of depression (OR: 1.76; 95% CI: 1.13-2.75).

CONCLUSIONS

Short sleep duration on both weekdays and weekends was found to be associated with depression. These findings suggest that sleep duration should be considered an important factor in the prevention of depression.

Twenty-four-hour Skin Temperature Rhythms in Young People With Emerging Mood Disorders: Relationships With Illness Subtypes and Clinical Stage

While circadian disruptions are common in some sub-groups of youth with mood disorders, skin temperature rhythms in these cohorts are understudied. We examined 24-h wrist skin temperature rhythms in youth with emerging mood disorders, exploring associations with clinical stage and proposed illness subtypes. Youth (n = 306, 23.42 ± 4.91 years, 65% females) accessing mental health care and 48 healthy controls (23.44 ± 3.38 years, 60% females) were examined. Skin temperature parameters including rhythm-adjusted mean temperature, inter-daily stability (day-to-day consistency), intra-daily variability (rhythm fragmentation), and peak temperature time were derived from a wearable sensor. Based on our illness trajectory-pathophysiology model, participants were classified by mood disorder subtypes ("hyperarousal-anxious" [n = 209], "neurodevelopmental-psychosis" [n = 40], or "circadian-bipolar spectrum" [n = 43]), as well as by clinical stage (subthreshold disorders classed as 1a or 1b [n = 47, 173, respectively], and full-threshold disorders as 2+ [n = 76]). Compared to controls, youth with mood disorders had delayed, less stable, and more variable skin temperature rhythms, indicated by lower rhythm-adjusted mean skin temperature (29.94 ± 0.10 °C vs 31.04 ± 0.25 °C, p < 0.001), delayed peak timing (0533 ± 0014 vs 0332 ± 0036, p = 0.002), reduced inter-daily stability (p = 0.009), and increased intra-daily variability (p = 0.020). Peak skin temperature also occurred later relative to sleep midpoint (0.31 ± 0.14 vs -0.48 ± 0.35 radians, p = 0.037). The "circadian-bipolar spectrum" subtype exhibited lower relative amplitude (0.07 ± 0.005 vs 0.08 ± 0.002 [hyperarousal-anxious] and 0.09 ± 0.005 [neurodevelopmental-psychosis], p = 0.039), with no delay in sleep midpoint. Clinical stages were not associated with differences in skin temperature parameters. These findings highlight the potential of use of 24-h skin temperature rhythms as a non-invasive biomarker of circadian disturbances in youth with emerging mood disorders. The observed disruptions in temperature patterns and rhythmicity support the notion that disrupted circadian rhythms may mediate the onset or illness course of some subgroups of youth with emerging major mood disorders.

Sleep as the Foundation of Brain Health

Sleep is a vital function, taking about one-third of a human lifetime, and is essential for achieving and maintaining brain health. From homeostatic neurophysiology to emotional and procedural memory processing to clearance of brain waste, sleep and circadian alignment remain paramount. Yet modern lifestyles and clinical practice often dismiss sleep, resulting in profound long-term repercussions. This chapter examines the roles of sleep and circadian rhythms in memory consolidation, synaptic plasticity, and clearance of metabolic waste, highlighting recent advances in neuroscience research. We explore how insufficient and disordered sleep-a public health concern-can impair cognition, escalate neurodegenerative risks, and compromise neurovascular integrity, thereby impacting brain health. These findings underscore the need for comprehensive screening for disturbed sleep and targeted interventions in clinical practice. Emerging interventions and AI-driven technologies may allow early detection and personalized and individualized treatments and improve outcomes. Overall, this chapter reaffirms that healthy sleep is indispensable at any level of neurological disease prevention-on par with the role of diet and exercise in cardiovascular health-and represents the foundation of brain health.

Multidimensional Sleep Health: Definitions and Implications for Cardiometabolic Health: A Scientific Statement From the American Heart Association

Poor sleep health is associated with cardiometabolic disease and related risk factors, including heart disease, stroke, elevated blood pressure and lipid levels, inflammation, glucose intolerance, obesity, physical inactivity, poor diet, unhealthy substance use, poor mental health, and increased all-cause and cardiovascular mortality, and is associated with social determinants of cardiovascular health and health disparities. Therefore, sleep duration has been recognized by the American Heart Association as one of Life's Essential 8. Although chronic sleep duration is the sole metric used in Life's Essential 8, sleep health represents a multidimensional construct. This scientific statement outlines the concept of multidimensional sleep health (sleep duration, continuity, timing, regularity, sleep-related daytime functioning, architecture, and absence of sleep disorders) as it applies to cardiometabolic health. Considerations of how these dimensions are related to cardiometabolic health and patterned by sociodemographic status are explained, and knowledge gaps are highlighted. Additional data are needed to understand better how these various dimensions of sleep should be assessed and how interventions targeting sleep health in clinical and community settings can be leveraged to improve health.

An experimental investigation of daily mental contrasting with implementation intentions and goal motives in reducing bedtime procrastination: a registered report

OBJECTIVES

Mental contrasting with implementation intentions (MCII) is an effective self-regulation strategy for goal pursuit. Although it is a quick and cost-effective strategy, most of its applications have consisted of single-time training. Building on the existing research on bedtime procrastination, we propose that daily MCII applications can lead to more efficient pursuit of bedtime goals. Furthermore, we evaluate the conditions where MCII training could be more advantageous for people with different types of goal motives.

METHODS AND MEASURES

We recruited 297 participants via Prolific and randomly allocated participants into either daily MCII or single MCII groups for a week-long diary study. We measured goal motives, goal-regulatory variables, bedtime procrastination, and affect to test our hypotheses. We conducted a multilevel structural equation modelling using Mplus.

RESULTS

Participants who completed MCII daily reported less bedtime procrastination than individuals who performed MCII one-off at the start of the week. Participants experienced increased positive affect and decreased negative affect when they procrastinated less. Autonomous goal motives were not associated with bedtime procrastination.

DISCUSSION

Daily MCII appears as an effective and easy-to-implement strategy helps reducing bedtime procrastination. Future research should test the effectiveness of daily MCII in other contexts.

Wearing WHOOP More Frequently Is Associated with Better Biometrics and Healthier Sleep and Activity Patterns

Wearable devices are increasingly used for health monitoring, yet the impact of consistent wear on physiological and behavioral outcomes is unclear. Leveraging nearly a million days and nights of longitudinal data from 11,914 subscribers, we examined the associations between the frequency of wearing a wrist-worn wearable device (WHOOP Inc., Boston, MA, USA) and 12-week changes in biometric, sleep, and activity profiles, modeling both between- and within-person effects. Higher average wear frequency and week-to-week increases in wear were associated with a lower resting heart rate (RHR), higher heart rate variability (HRV), longer and more consistent sleep, and greater weekly and daily physical activity duration (Ps < 0.01). A within-person multiple mediation analysis indicated that increased sleep duration partially mediated the association between wear frequency and a standardized (z-scored) RHR (indirect effect = -0.0387 [95% CI: -0.0464, -0.0326]), whereas physical activity minutes did not (indirect effect = 0.0003 [95% CI: -0.0036, 0.0040]). A Granger causality analysis revealed a modest but notable association between prior wear frequency and future RHR in participants averaging ≤5 days of weekly wear (p < 0.05 in 10.92% of tests). While further research is needed, our findings provide real-world evidence that sustained wearable engagement may support healthier habits and improved physiological outcomes over time.

Circadian phase in high-school students: weekday-weekend shifts and relationships to other sleep/circadian characteristics

STUDY OBJECTIVES

In a sample of high-school students, (1) to characterize within-person changes in sleep and circadian characteristics from school nights to weekend nights, (2) to examine whether later circadian phase relates to weekday-weekend changes in sleep/circadian characteristics, and (3) to examine correlations between biological and proxy measures of circadian phase.

METHODS

Sample included 95 high-school students reporting at least one drink of alcohol in their lifetime. Participants completed baseline self-report measures, wrist actigraphy for 8 days, and two overnight laboratory visits (Thursday and Sunday) for salivary melatonin sample collection. Circadian phase was calculated as the dim light melatonin onset (DLMO; 4 pg/mL threshold). Proxy circadian phase measures included the Composite Scale of Morningness (CSM), Munich Chronotype Questionnaire (MCTQ), and actigraphy-based midsleep.

RESULTS

Other than nap duration, all examined actigraphy-based sleep characteristics, DLMO, and DLMO-sleep phase angles showed weekday-weekend differences (adjusted p-value < .05). Later mean DLMO was associated with larger weekday-weekend changes in total sleep time (b = 0.39, padjusted = .010). CSM and actigraphy-based midsleep showed small-to-moderate (rho = ~0.3) and moderate (rho = ~0.5) correlations with DLMO, respectively, but chronotype based on the MCTQ was not correlated with DLMO.

CONCLUSIONS

In the largest published sample to date, circadian phase substantially shifted from the school week to weekend, underscoring the "social jetlag" imposed by early school start times. Similarly, teens with the latest circadian phase exhibited the greatest weekend catch-up sleep. Finally, perhaps due to the instability of circadian phase in this context, self-reported proxies for circadian timing were poor approximations of biological circadian phase.

Clinical physiology of circadian rhythms: A systematic and hierarchized content analysis of circadian questionnaires

Circadian rhythms are near-24 h patterns of physiology and behavior associated with several physical and mental health outcomes. Self-report questionnaires are routinely used and practical tools to assess circadian rhythms. However, the extent to which these questionnaires capture the relevant parameters and can be used interchangeably is unknown. We investigated different types of circadian manifestations using 14 circadian self-report questionnaires for adults. A systematic and hierarchical content analysis was combined with a visualization method. Jaccard indices were calculated to quantify the degree to which the questionnaires overlapped. Content analysis revealed 40 distinct manifestations, which we classified into five dimensions ("circadian phase," "circadian amplitude and stability," "nycthemeral timing," "nycthemeral regularity," and "circadian complaints"). The average Jaccard index was 0.150, indicating very weak content overlap. None of the 14 questionnaires explored all five dimensions. The Composite Scale of Morningness and the Morningness-Eveningness Questionnaire exhibited greater, but still limited, overlap with the other questionnaires (Jaccard indices of 0.255 and 0.251, respectively), and are the best instruments for assessing the circadian phase. Nycthemeral timing, which must be analyzed to measure the circadian misalignment in clinical and research settings, is only explored by the Munich Chronotype Questionnaire, but that instrument does not evaluate circadian amplitude and stability and only partially assesses nycthemeral regularity. Based on our preliminary analysis, we make recommendations regarding the circumstances in which some circadian questionnaires could prove more useful than the others. The results might also aid the definition and investigation of circadian health at the crossroads of physiology and behavior.

Painful Mondays: Exploring Weekly Sleep Variations and Pain Perception in Healthy Women-An Experimental Study

BACKGROUND

Acute experimental sleep deprivation induces pain hypersensitivity, particularly in females. While the impact of extreme sleep loss on pain perception has been largely studied, how subtle sleep fluctuations, for example, sleep variations across the week, affect pain perception remains unclear. This study investigated how weekly sleep variations affect pain perception in young healthy women.

METHODS

A sleep-monitoring headband and self-reported questionnaire were used to assess sleep. Quantitative sensory testing was conducted on Monday and Friday, including heat, cold, pressure pain thresholds, tonic pain summation and conditioned pain modulation.

RESULTS

A total of 26 healthy young (23.9 ± 0.9 years) women were included. Repeated measures ANOVAs revealed significant sleep variation across the week, including differences in N3 sleep stage duration (M = 89.2 ± 5.42 min; p = 0.022, lowest on Friday and Sunday nights), bedtime (M = 00:56 AM ± 0.29; p = 0.038, latest on Friday vs. Sunday night) and wake-up time (M = 07:04 AM ± 0.30; p = 0.007 latest on Saturday vs. Monday morning). With most changes affecting Sunday night and Monday morning, pain sensitivity was higher on Monday compared to Friday, with a lower heat pain threshold (B = -11.89; p = 0.002) and increased heat pain summation (B = 1.65; p < 0.001).

CONCLUSIONS

The results showed higher heat pain hyperalgesia on Mondays due to weekly sleep variation. Since sleep is a modifiable factor, maintaining a consistent sleep schedule throughout the week could benefit pain management, particularly in chronic pain patients with less effective pain modulatory pathways.

STATEMENT OF SIGNIFICANCE

How weekly sleep variations in real life between weekends and weekdays affect pain perception has not been studied before. This paper provides the first evidence that natural weekend-weekday sleep alterations, including shifts in bedtime and wake-up time over the weekend and the transition back on Sunday night, heighten pain sensitivity on Monday-known as the 'Monday effect'. The compromised pain pathways on Monday underscore the importance of maintaining a consistent sleep schedule throughout the week, potentially benefiting patients with chronic pain.

STUDY PREREGISTRATION STATEMENT

The authors have nothing to report.

Exploring the link between sleep patterns and early cardiovascular disease markers in young adults with chronic anxiety

Chronic anxiety is commonly associated with poor sleep patterns, which may contribute to an increased risk of cardiovascular disease (CVD) through mechanisms like oxidative stress, vascular dysfunction, and poor blood pressure control. As sleep disturbances, particularly poor sleep quality and/or regularity, have been independently linked to CVD development, this study explored whether sleep quality/regularity in young adults with chronic anxiety is associated with early indicators of CVD risk, specifically oxidative stress, vascular function, and blood pressure control. Twenty-eight young (24 ± 4 yr) participants with a prior clinical diagnosis of generalized anxiety disorder (GAD) or elevated GAD symptoms (GAD-7 > 10) had their sleep quality [total sleep time (TST) and sleep efficiency (SE)] and regularity [via TST/SE standard deviations (SD)] assessed for seven consecutive days. Various precursors to CVD development such as oxidative stress, brachial artery function, microvascular function, and blood pressure control [exercise pressor responses and cardiovagal baroreflex sensitivity (cBRS)] were also evaluated. Pearson's correlations were used to determine potential relationships between sleep quality/regularity and CVD precursors. Both sleep irregularity variables [SE-SD (r = 0.61; P < 0.01) and TST-SD (r = 0.39; P = 0.04)], but neither of the sleep quality variables, were positively correlated with oxidative stress. TST-SD alone was significantly associated with lower brachial artery function (r = -0.44; P = 0.02) and cBRS (r = 0.43; P = 0.02), with TST-SD median splits further highlighting these differences. The study found that irregular TST in individuals with chronic anxiety was significantly associated with higher oxidative stress, lower brachial artery function, and blunted blood pressure control (lower cBRS), key precursors of CVD.NEW & NOTEWORTHY This study examined the relationship between sleep irregularity and early cardiovascular disease (CVD) precursors in young adults with chronic anxiety. Key findings revealed that irregular total sleep time, rather than overall sleep quality, was significantly associated with greater oxidative stress, lower brachial artery function, and diminished blood pressure control. These results suggest that sleep irregularity in individuals with chronic anxiety may play a critical role in the development of CVD in this population.

Impact of postpartum physical activity on maternal sleep: a systematic review and meta-analysis

OBJECTIVE

To examine the relationship between postpartum physical activity and maternal sleep.

DESIGN

Systematic review with random-effects meta-analysis. Online databases were searched through 20 January 2025.

STUDY ELIGIBILITY CRITERIA

Studies of all designs (except case studies and reviews) in all languages were eligible if they contained information on the population (individuals up to 1 year post partum); interventions/exposures (including subjective or objective measures of frequency, intensity, duration, volume or type of exercise, alone ('exercise only') or in combination with other intervention components (eg, dietary; 'exercise+co-intervention')); comparator (low volume or no physical activity) and outcomes: sleep duration, quality, latency, efficiency, disturbance and fatigue.

RESULTS

12 unique studies (n=3096) from nine countries were included. Moderate certainty of evidence showed that exercise-only interventions were associated with a greater improvement in sleep quality (five randomised controlled trials (RCTs), n=375, standardised mean difference (SMD) -0.44, 95% CI -0.79 to -0.09) compared with no exercise. High certainty of evidence showed that exercise interventions were associated with a greater improvement in daytime/general fatigue (six RCTs, n=535, SMD -0.56, 95% CI -1.06 to -0.05) compared with no exercise. No effect was found for sleep duration, latency, efficiency, or disturbance.

CONCLUSION

Postpartum physical activity improves maternal sleep quality and daytime/general fatigue.

Impaired sleep, depressive symptoms, and pain as determinants of physical activity and exercise intervention adherence: an exploratory analysis of a randomized clinical trial

BACKGROUND

Physical activity (PA) and exercise interventions offer health benefits can reduce dementia risk. However, there might be barriers to engage in PA, such as sleep problems, depressive symptoms and pain, which are common complaints with older adults. We investigated sleep duration, sleep quality, depressive symptoms, and pain at baseline as potential determinants of: (i) adherence to the exercise intervention component of a 2-year multidomain lifestyle intervention; (ii) intervention's effect on PA after 2 years; and (iii) overall PA after 2 years (exploratory analyses).

METHODS

The FINGER trial included 1259 individuals at risk for dementia, aged 60-77 years who were randomized (1:1) to a multidomain lifestyle intervention (exercise, diet, cognitive training, vascular risk factor management) or a control (regular health advice) group. Logistic regression analyses were used with exercise adherence (adherent: ≥66% participation) or self-reported PA (active: ≥2 times/week) as outcomes, adjusted for relevant baseline characteristics. Data on PA at baseline and at 2-years were available for 1100 participants.

RESULTS

Adherence to the exercise intervention was less likely with sleep duration < 6 h or ≥ 9 h per night compared with 7-8 h. OR (95% CI) were 0.46 (0.21-0.99) and 0.38 (0.20-0.74), respectively. The intervention group was more likely to be physically active than the control group at two years (OR 1.87, 95% CI 1.36-2.55). This intervention benefit did not significantly vary by baseline sleep duration, depressive symptoms, or pain (p > 0.3 for all interactions). Regardless of randomization group, those sleeping < 6 h were less likely to be physically active at two years, compared with participants sleeping 7-8 h (OR 0.36, 95% CI 0.18-0.72). Depressive symptoms or pain were not related to PA at two years.

CONCLUSIONS

Older adults with sleep problems, depressive symptoms, or pain may benefit from lifestyle interventions. However, both short and long sleep duration can pose barriers to engaging in exercise intervention and should be carefully considered when designing strategies to promote PA among older populations at risk for dementia.

TRIAL REGISTRATION

The FINGER trial was registered at ClinicalTrials.gov with identifier NCT01041989 on 04/01/2010.

Validation of a Neurophysiological-Based Wearable Device (Somfit) for the Assessment of Sleep in Athletes

The aim of the study was to examine the validity of a neurophysiological-based wearable device, i.e., Somfit (Compumedics Ltd.), for the assessment of sleep in athletes. Twenty-seven athletes (14 F, 13 M, aged 22.3 ± 5.1 years) spent a single night in a sleep laboratory. The participants had 9 h in bed (23:00-08:00) while fitted simultaneously with Somfit and polysomnography (PSG), i.e., the gold standard for the assessment of sleep. Somfit and PSG were used to independently categorise each 30-s epoch of time in bed into one of five states, i.e., wake, stage 1 non-REM sleep (N1), stage 2 non-REM sleep (N2), stage 3 non-REM sleep (N3), or REM sleep. There were large differences between participants in terms of the amount of Somfit data that were successfully captured/scored, so three subsets were considered in the subsequent analyses: unfiltered subset (n = 26)-all participants, except one for whom no Somfit data were captured/scored; good-capture subset (n = 15)-participants for whom > 80% of Somfit data were captured/scored; excellent-capture subset (n = 7)-participants for whom > 99.9% of Somfit data were captured/scored. Agreement for the five-state categorisation of time in bed was calculated as the percentage of PSG epochs correctly scored by Somfit as N1, N2, N3, REM, or wake. Agreement (and Cohen's kappa) was 63% (0.47) for the unfiltered subset, 66% (0.52) for the good-capture subset, and 79% (0.70) for the excellent-capture subset. These data indicate a moderate-substantial level of agreement between Somfit and PSG for the assessment of sleep in athletes. Wearable devices that can capture valid sleep data may also be used to derive important measures related to the circadian system, such as sleep consistency and social jet lag.

Sleep health profiles across six population-based cohorts and recommendations for validating clustering models

OBJECTIVES

Model-based clustering is increasingly used to identify multidimensional sleep health profiles. However, generalizability is rarely assessed because of complexities of data sharing and harmonization. Our goal was to evaluate the generalizability of multidimensional sleep health profiles across older adult populations in Western countries and assess whether they predict depressive symptoms over time.

METHODS

We harmonized five self-reported sleep health indicators (satisfaction, alertness, timing, efficiency, and duration) across six population-based cohorts from the United States and Netherlands (N=614 - 3209 each) and performed identical latent class analysis in each cohort. Novel multivariable similarity metrics, patterns of sleep health and cluster sizes were used to match clusters and assess generalizability across cohorts. We compared cluster characteristics cross-sectionally and used linear mixed-effects modeling to relate sleep health clusters to depressive symptoms over time.

RESULTS

"Average sleep health" (moderate duration; high quality/efficiency; 42.7%-76.7% of sample) and "poor sleep health" (short duration; low quality/efficiency; high daytime sleepiness; 9.4%-20.4% of sample) clusters were generalizable across cohorts. In four cohorts "inefficient sleep" clusters were identified and in two cohorts "long, efficient sleep" clusters were identified. At 3years, those in the poor sleep cluster had depression symptoms that were 1.40-2.79 times greater than in the average sleep cluster, across all cohorts.

CONCLUSIONS

We identified two profiles - average sleep health and poor sleep health - that were generalizable across six samples of older adults and predicted depressive symptoms, underscoring the importance of the sleep health paradigm.

Mapping the Neural Basis of Wake Onset Regularity and Its Effects on Sleep Quality and Positive Affect

The regularity of sleep-wake cycles is a defining characteristic of normative sleep patterns that are typically associated with proper circadian rhythmicity. The previous literature indicates that consistent patterns of sleep and wake are associated with improved sleep quality and cognitive functioning. Conversely, sleep irregularity has been associated with reduced well-being and inefficiency in resting-state neural networks. This study investigated the relationship between specific sleep regularity measures and outcomes, including emotional affect, sleep quality, and resting-state functional connectivity. We found that variability in wake onset predicted poorer sleep quality and reduced positive affect. Furthermore, sleep regularity measures were associated with altered functional connectivity between the posterior cingulate cortex and regions involved in emotional processing. We propose that alterations in default mode network (DMN) connectivity linked to sleep irregularity reflect disruptions in emotional processing and sleep quality.

A replicate crossover trial on the interindividual variability of sleep indices in response to acute exercise undertaken by healthy men

STUDY OBJECTIVES

Using the necessary replicate-crossover design, we investigated whether there is interindividual variability in home-assessed sleep in response to acute exercise.

METHODS

Eighteen healthy men (mean [SD]: 26[6] years) completed two identical control (8 hour laboratory rest, 08:45-16:45) and two identical exercise (7 hour laboratory rest; 1 hour laboratory treadmill run [62(7)% peak oxygen uptake], 15:15-16:15) trials in randomized sequences. Wrist-worn actigraphy (MotionWatch 8) measured home-based sleep (total sleep time, actual wake time, sleep latency, and sleep efficiency) two nights before (nights 1 and 2) and three nights after (nights 3-5) the exercise/control day. Pearson's correlation coefficients quantified the consistency of individual differences between the replicates of control-adjusted exercise responses to explore: (1) immediate (night 3 minus night 2); (2) delayed (night 5 minus night 2); and (3) overall (average post-intervention minus average pre-intervention) exercise-related effects. Within-participant linear mixed models and a random-effects between-participant meta-analysis estimated participant-by-trial response heterogeneity.

RESULTS

For all comparisons and sleep outcomes, the between-replicate correlations were nonsignificant, ranging from trivial to moderate (r range = -0.44 to 0.41, p ≥ .065). Participant-by-trial interactions were trivial. Individual differences SDs were small, prone to uncertainty around the estimates indicated by wide 95% confidence intervals, and did not provide support for true individual response heterogeneity. Meta-analyses of the between-participant, replicate-averaged condition effect revealed that, again, heterogeneity (τ) was negligible for most sleep outcomes.

CONCLUSIONS

Control-adjusted sleep in response to acute exercise was inconsistent when measured on repeated occasions. Interindividual differences in sleep in response to exercise were small compared with the natural (trial-to-trial) within-subject variability in sleep outcomes.

CLINICAL TRIALS INFORMATION

https://clinicaltrials.gov/study/NCT05022498. Registration number: NCT05022498.

Sleep regularity and major adverse cardiovascular events: a device-based prospective study in 72 269 UK adults

BACKGROUND

This study examines the associations between device-measured sleep regularity and the risk of major adverse cardiovascular events (MACE), and aims to determine whether sufficient sleep duration attenuates or eliminates the effects of irregular sleep on MACE risk.

METHODS

A prospective cohort study of adults aged 40-79 years from the UK Biobank who wore wrist-attached accelerometers for 7 days was conducted. Sleep Regularity Index (SRI) scores were calculated for each participant using a validated algorithm, and categorised as irregular (SRI <71.6), moderately irregular (SRI between 71.6 and 87.3), and regular (SRI >87.3 (reference group)). Information on MACE and its subtypes (myocardial infarction, heart failure, stroke) was obtained from inpatient hospitalisation and death records.

RESULTS

We analysed data from 72 269 individuals followed for 8 years, without a previous history of MACE and without an event in the first year of follow-up. Irregular (HR 1.26, 95% CI 1.16 to 1.37) and moderately irregular sleepers (HR 1.08, 95% CI 1.01 to 1.70) were at higher risk of MACE compared with regular sleepers. Dose-response analyses treating SRI as a continuous measure showed that SRI was associated with MACE risk in a near-linear fashion, with a steeper MACE risk reduction at higher (better) SRI scores. Joint SRI and sleep duration analyses showed that meeting the age-specific sleep duration recommendation offsets MACE risk for moderately irregular sleepers (HR 1.07, 95% CI 0.96 to 1.18), but not for irregular sleepers (HR 1.19, 95% CI 1.06 to 1.35).

CONCLUSIONS

Irregular sleep was strongly associated with higher MACE risk. Adequate sleep duration was not sufficient to offset these adverse effects among irregular sleepers. This study supports the inclusion of sleep regularity in public health guidelines and clinical practice as a risk factor for cardiovascular disease.

Individual and Combined Association Between Healthy Behaviors and All-Cause and Premature Mortality: A 22-Year Follow-up Cohort

OBJECTIVE

To analyze the impact of individual and combined healthy behaviors on all-cause and premature mortality risk in Mexican adults.

METHODS

Data on physical activity, fruit and vegetable intake, sleep hours, alcohol intake, and smoking from 95,142 adults from the MCPS (Mexico City Prospective Study) were used. All-cause mortality was monitored for up to 22 years, until December 31, 2020. Cox proportional hazards regression was used to assess mortality risk.

RESULTS

Physical activity (HR, 0.88; 95% CI, 0.84 to 0.92), fruit and vegetable intake (HR, 0.94; 95% CI, 0.91 to 0.98), no excessive alcohol consumption (HR, 0.86; 95% CI, 0.81 to 0.92), and not smoking (HR, 0.93; 95% CI, 0.89 to 0.97) were individually associated with lower mortality. All-cause mortality risk decreased progressively by 8% (95% CI: 0.86 to 0.99) to 29% (95% CI, 0.63 to 0.81) for each additional healthy behavior attained. Similarly, premature mortality risk decreased by 13% (95% CI, 0.80 to 0.95) to 30% (95% CI, 0.59 to 0.83).

CONCLUSION

Over 22 years, adopting a healthier life was linked with lower all-cause and premature mortality risk, decreasing with the clustering of one additional healthy behavior. Law and policy changes as well as efforts to address the root causes of not adopting healthy behaviors in low- and middle-income countries, such as creating structural conditions for people to engage in physical activity or strong social marketing to raise awareness of the daily consumption of fruits and vegetables, are needed for improving health and delaying mortality.

A good night's rest: A contemporary review of sleep and cardiovascular health

Sleep is increasingly recognized as a significant contributor to the development of cardiovascular disease (CVD). Recent American Heart Association guidelines incorporate sleep duration into the "Life's Essential Eight" framework of ideal cardiovascular health. This article will review the evidence relating sleep duration, regularity, and quality with all-cause and cardiovascular mortality, cardiometabolic syndrome, and coronary artery disease in adults. Short sleep duration is strongly associated with cardiovascular mortality, cardiometabolic risk factors, and coronary artery disease. Limited studies also suggest a possible U-shaped association, with long sleep duration also associated with greater cardiovascular risk. Sleep regularity has emerged as a strong and independent risk factor for CVD-related mortality, cardiometabolic syndrome, and subclinical atherosclerosis. Less is known about the impact of sleep quality on CVD, though a number of observational studies suggest a possible association with metabolic syndrome and subclinical atherosclerosis. This review provides an update of the literature on the cardiovascular impact of sleep for the everyday clinician and highlights gaps in knowledge that warrant future research.

Relationship between development trajectories of leisure activity and sleep time on incident cognitive impairment: A study based on the Chinese Longitudinal Healthy Longevity Survey (CLHLS)

BackgroundLeisure activity and sleep time are key factors in cognitive impairment, but the impact of their long-term trajectories on incident cognitive impairment remains unclear.ObjectiveTo examine the association of leisure activity trajectories, sleep time trajectories and their combined effects with incident cognitive impairment in older adults.MethodsData from the Chinese Longitudinal Healthy Longevity Survey (2008-2018) were analyzed, including adults aged ≥65 who participated in at least three surveys. Group-based trajectory modeling explored leisure activity and sleep time patterns. Cox proportional-hazards regression model assessed the association of leisure activity trajectories and sleep time trajectories and their combined effects with incident cognitive impairment.ResultsWe included 3094 participants with a median follow-up of 6.07 years. The optimal trajectory groups for leisure activity and sleep time were four and three, respectively. The low-level leisure activity group were associated with an increased risk of cognitive impairment (HR, 95%CI: 2.07, 1.37-3.13), whereas the high-level leisure activity group were associated with a reduced risk of cognitive impairment (HR, 95%CI: 0.60, 0.36-0.99). Short sleep time group was associated with a reduced risk of cognitive impairment (HR, 95%CI: 0.62, 0.41-0.92). In the combined effect, leisure activity belonging to the low-level group and sleep time belonging to the moderate sleep time group or the long sleep time group were associated with an increased risk of cognitive impairment.ConclusionsLong-term high-level leisure activity and short sleep time are associated with a reduced risk of cognitive impairment in older adults.

Sleep: The silent hero in cardiometabolic health

The essential role of sleep in overall health is increasingly recognized, yet it remains underemphasized in both clinical and public health contexts. Despite extensive research linking poor sleep health to chronic conditions such as cardiovascular disease, type 2 diabetes, and cognitive decline, sleep health is not routinely assessed or integrated into standard care practices. Sleep problems, including insomnia, sleep apnea, and poor sleep quality, are prevalent globally, affecting over 30 % of the population and contributing to significant public health burdens like cardiometabolic disease, mental health disorders and multimorbidity. The economic implications are substantial, with insufficient sleep imposing significant societal and financial costs worldwide. Recognizing this, recent initiatives like the American Heart Association's inclusion of sleep in the Life's Essential 8 framework highlight the importance of sleep in cardiometabolic health. Integrating sleep into clinical and public health strategies is crucial, due to the wide-ranging impact of sleep on cardiometabolic health. Social, environmental, and demographic factors also play significant roles in sleep health, with lower socioeconomic groups and women often experiencing poorer sleep, further exacerbating health disparities. Adopting a life course approach and promoting healthy sleep behaviors early in life are essential for mitigating long-term cardiometabolic risks. Effective evidence-based strategies for improving sleep behaviors and cardiometabolic health, beyond addressing sleep disorders, include prioritizing sleep hygiene, managing stress, promoting physical activity, maintaining a healthy diet, and reducing substance use, all of which contribute to overall well-being. In conclusion, incorporating sleep health into routine cardiometabolic risk stratification, prevention, and management is essential for improving overall health outcomes.

Validation of the Caen Chronotype Questionnaire: Exploring the added value of amplitude and correlations with actigraphy

Chronotype self-report instruments are time and cost-efficient measures to profile diurnal or time-of-day preferences. The Caen Chronotype Questionnaire (CCQ) captures morningness and eveningness (CCQ-ME) and a circadian amplitude dimension for diurnal variation (distinctiveness; CCQ-DI). This study extends prior multilanguage validations for the English version of the CCQ. In total, 628 participants enrolled from a UK working population (mean age 30.34 ± 8.36 years, 61.3% female) including a subset of shift workers (n = 179; mean age 27.62 ± 5.95 years, 49.2% female). A subsample of participants also wore a consumer-grade actigraph device (Fitbit Charge 4) for seven days to compare chronotype estimates with objective sleep-wake parameters (n = 22; mean age 27.05 ± 3.99 years, 81.8% female, 90.9% worked standard daytime schedules, and 9.1% worked rotating shifts). All participants completed online chronotype measures, including the CCQ and Morningness-Eveningness Questionnaire (MEQ), depressive symptoms (Patient Health Questionnaire; PHQ-9), sleep quality (Pittsburgh Sleep Quality Index; PSQI), and other outcome measures. Results from the Confirmatory Factor Analysis (CFA) offer support for a two-factor structure of the CCQ in an English-speaking sample, highlighting how individual preferences for the timing of activities is associated with chronotype (morningness-eveningness; ME) and a second subjective amplitude dimension (DI). However, in contrast with the original CCQ structure, a more parsimonious solution and best overall fit involved the reduction of the original 16-item questionnaire (8 items per factor) to 4 ME items and 5 DI items. Convergent validity with the reduced CCQ scale (rME) and the MEQ was also established. The CCQ was sensitive in discriminating differences in actigraphic sleep-wake timings between morning-and evening-oriented individuals. Regression models demonstrated that amplitude (CCQ-DI) was a significant predictor explaining most of the variance in depressive symptoms (PHQ-9) compared to other variables. Overall, the English version of the CCQ was shown to be a robust tool in estimating chronotype in a sample of adults based in the UK.

The Past and Future of Sleep Medicine

The past of sleep medicine is rich with seminal discoveries, from the recognition of clinical syndromes to measurement of sleep itself to classic and novel therapeutics. Advances in neurobiology have mapped a number of sleep circuits, described the central and peripheral circadian system, and identified the cause of narcolepsy with cataplexy. Sleep apnea endotypes and phenotypes now have established clinical relevance, though treatment implications are a work in progress. Artificial intelligence will continue to change sleep medicine in a number of domains from aiding scoring to health outcome predictions. There is a large gap between the known science and clinical translational.

Sleep irregularity is associated with night-time technology, dysfunctional sleep beliefs and subjective sleep parameters amongst female university students

Sleep irregularity has been linked to multiple deleterious consequences in clinical populations or community adults and adolescents, but little is known about young adults. In this study, we explored the relationships between two measures of sleep regularity and a wide range of factors (lifestyle behaviors, subjective sleep, clinical outcomes, and academic performance) in a sample of female, university students in the United Arab Emirates. A total of 176 participants were recruited. Objective estimates of sleep-wake patterns were obtained using seven-day wrist actigraphy and data were used to calculate daily sleep regularity with the Sleep Regularity Index (SRI) and weekly sleep regularity with the social jetlag (SJL). Subjective sleep measures were also acquired using the Pittsburgh Sleep Quality Index (PSQI), Dysfunctional Beliefs and Attitudes about Sleep (DBAS), and daytime napping frequency. Self-reported night-time technology use frequency was ascertained using the Technology Use Questionnaire (TUQ). Psychological health was assessed using the Hospital Anxiety and Depression Scale. Objective physical health measurements for body mass index, fasting blood glucose and blood pressure were obtained. No significant associations emerged between sleep regularity and psychological physical health, or academic performance. However, significant relationships were detected between SRI and daytime napping frequency (p-value = 0.0017), PSQI (p-value = 0.0337), and DBAS (p-value = 0.0176), suggesting that daily irregular sleep patterns are associated with more frequent daytime napping, greater dysfunctional sleep beliefs, and poorer subjective sleep quality. Conversely, SJL was significantly associated with the DBAS (p-value = 0.0253), and the TUQ (p-value = 0.0208), indicating that weekly irregular sleep patterns are linked to greater dysfunctional sleep beliefs and increased nighttime technology use. In conclusion, efforts to educate and cultivate sustainable and consistent sleep-wake patterns amongst university students are needed, which can be achieved by raising awareness, promoting good sleep health habits, and minimizing excessive bedtime technology.

Determining the influence of a sleep improvement intervention on medical students' sleep and fatigue: protocol of the PROMESS-Sleep clinical trial

BACKGROUND

Medical students face a demanding workload, stressful situations, and irregular sleep patterns, which can lead to elevated sleep disturbances and high fatigue levels. These difficulties may be further associated with a major decline in well-being, quality of life, performance, and health. Thus, these struggles must be addressed to reduce these students' sleep disturbances and fatigue during their curriculum.

METHODS

The PROMESS-Sleep clinical trial aims to support future healthcare professionals by enhancing their abilities to manage their sleep. The support will be provided through a three-session sleep management program. Each session will include an individual meeting between a PROMESS-Sleep expert and a medical student, during which self-care education, advice, and personalized goals will be established. The present protocol is designed to assess the influence of this program on 45 undergraduate medical students (fourth- and fifth-year) of the Lyon-Est Faculty of Medicine (Claude Bernard University Lyon 1, France). Assessments of sleep and fatigue will be conducted before and during the intervention using self-reported questionnaires and actigraphy. At the end of the third session, the student's satisfaction levels regarding the program will be assessed. The primary outcome will be changes in scores on the Pittsburgh Sleep Quality Index (PSQI) during the program. Secondary outcomes will provide a detailed characterization of changes in various aspects of sleep disturbances, fatigue, sleep habits, and sleep-wake rhythms. Exploratory outcomes will provide information regarding the students' satisfaction levels and will determine the moderators of the program's efficacy. Data will be analyzed according to the intention-to-treat principle and presented in accordance with the CONSORT Guidelines. Ethical approval has been obtained by the Institutional Review Board (IRB: 2023-07-04-03), and all procedures will be performed in adherence to the Helsinki Declaration. The results from this study will be presented at scientific conferences and in peer-reviewed scientific journals.

DISCUSSION

The results will provide valuable insights into the program's efficacy in reducing sleep disturbances and fatigue. If its efficacy is proven, PROMESS-Sleep could become an integral and sustainable part of medical education due to fostering a healthier and more resilient future for healthcare professionals. This manuscript follows the SPIRIT guidelines (Additional files 1 & 8).

TRIAL REGISTRATION

ClinicalTrials.gov: NCT06297330; retrospectively registered.

Sleep disturbances across 2 weeks predict future mental healthcare utilization

STUDY OBJECTIVES

Insufficient sleep costs the US economy over $411 billion per year. However, most studies investigating the economic costs of sleep rely on one-time measures of sleep, which may be prone to recall bias and cannot capture variability in sleep. To address these gaps, we examined how sleep metrics captured from daily sleep diaries predicted medical expenditures.

METHODS

Participants were 391 World Trade Center (WTC) responders enrolled in the WTC Health Program (mean age = 54.97 years, 89% men). At baseline, participants completed 14 days of self-reported sleep and stress measures. Mean sleep, variability in sleep, and a novel measure of sleep reactivity (i.e. how much people's sleep changes in response to daily stress) were used to predict the subsequent year's medical expenditures, covarying for age, race/ethnicity, sex, medical diagnoses, and body mass index.

RESULTS

Mean sleep efficiency did not predict mental healthcare utilization. However, greater sleep efficiency reactivity to stress (b = $191.75, p = .027), sleep duration reactivity to stress (b = $206.33, p = .040), variability in sleep efficiency (b = $339.33, p = .002), variability in sleep duration (b = $260.87, p = .004), and quadratic mean sleep duration (b = $182.37, p = .001) all predicted greater mental healthcare expenditures. Together, these sleep variables explained 12% of the unique variance in mental healthcare expenditures. No sleep variables were significantly associated with physical healthcare expenditures.

CONCLUSIONS

People with more irregular sleep, more sleep reactivity, and either short or long sleep engage in more mental healthcare utilization. It may be important to address these individuals' sleep problems to improve mental health and reduce healthcare costs.

A Multimodal Sleep Foundation Model Developed with 500K Hours of Sleep Recordings for Disease Predictions

Sleep is a fundamental biological process with profound implications for physical and mental health, yet our understanding of its complex patterns and their relationships to a broad spectrum of diseases remains limited. While polysomnography (PSG), the gold standard for sleep analysis, captures rich multimodal physiological data, analyzing these measurements has been challenging due to limited flexibility across recording environments, poor generalizability across cohorts, and difficulty in leveraging information from multiple signals simultaneously. To address this gap, we curated over 585,000 hours of high-quality sleep recordings from approximately 65,000 participants across multiple cohorts and developed SleepFM, a multimodal sleep foundation model trained with a novel contrastive learning approach, designed to accommodate any PSG montage. SleepFM produces informative sleep embeddings that enable predictions of future diseases. We systematically demonstrate that SleepFM embeddings can predict 130 future diseases, as modeled by Phecodes, with C-Index and AUROC of at least 0.75 on held-out participants (Bonferroni-corrected p < 0.01). This includes accurate predictions for death (C-Index: 0.84 [95% CI: 0.81-0.87]), heart failure (C-Index: 0.80 [95% CI: 0.77-0.83]), chronic kidney disease (C-Index: 0.79 [95% CI: 0.77-0.81]), dementia (C-Index: 0.85 [95% CI: 0.82-0.87]), stroke (C-Index: 0.78 [95% CI: 0.76-0.81]), atrial fibrillation (C-Index: 0.78 [95% CI: 0.75-0.81]), and myocardial infarction (C-Index: 0.81 [95% CI: 0.78-0.84]). The model's generalizability was further validated through strong performance on the Sleep Heart Health Study (SHHS), a dataset unseen during pre-training. Additionally, SleepFM demonstrates strong performance on traditional sleep analysis tasks, achieving competitive results in both sleep staging (mean F1 scores: 0.70-0.78) and sleep apnea diagnosis (AUROC: 0.90-0.94). Beyond these standard applications, our analysis reveals that specific sleep stages and physiological signals carry distinct predictive power for different diseases. This work demonstrates how foundation models can leverage sleep polysomnography data to uncover the extensive relationship between sleep physiology and future disease risk.

Dose-response associations of device-measured sleep regularity and duration with incident dementia in 82391 UK adults

BACKGROUND

Sleep is a crucial lifestyle factor with impacts on mental and cognitive health. The associations between objectively measured sleep and risk of incident dementia are not yet fully understood. To evaluate the associations of device-measured sleep duration and regularity with incident dementia and explore whether sleep regularity moderates the association of sleep duration with dementia.

METHODS

Population-based prospective cohort study of 82,391 adults aged 43 to 79 years from the UK Biobank accelerometry subsample, collected between 2013 and 2015, followed up to 2022. Device-based sleep duration (h/day) and sleep regularity index (SRI), a metric ranging from 0-100 that quantifies a person's sleep regularity (with a greater value indicating higher consistency), were calculated from wrist-worn accelerometry data recorded over the course of one week. Incident all-cause dementia cases were obtained from national hospital admission, primary care and mortality data followed up to 30 November 2022. We used Cox proportional hazard models to estimate the hazard ratios (HRs) for incident dementia after adjustment for common demographic and clinical covariates.

RESULTS

Over a mean follow-up of 7.9 years, 694 incident dementia cases occurred. We observed a U-shaped association between sleep duration and incident dementia, with only short sleep (< 7 h) being significantly associated with a higher risk of dementia. The median sleep duration for short sleepers (< 7 h) of 6.5 h, compared to the reference point of 7.9 h was associated with HR of 1.19 (95%CI 1.01,1.40) for incident dementia. Sleep regularity was negatively associated with dementia risk in a near-linear fashion (linear p = 0.01, non-linear p = 0.57). When we dichotomized sleep regularity, those in the higher sleep regularity group (SRI ≥ 70) had an HR of 0.74 (95%CI 0.63, 0.87) compared to those with lower sleep regularity (SRI < 70). The beneficial associations between sleep regularity and incident dementia were present only among participants with short (< 7 h) and long (≥ 8 h) sleep duration.

CONCLUSIONS

Assuming that the associations we observed are causal, maintaining a regular sleep pattern may help offset the deleterious association of inadequate sleep duration with dementia. Interventions aimed at improving sleep regularity may be a viable option for people not able to achieve the recommended hours of sleep.

Association between weekend catch-up sleep and hypertension of the United States population from 2017 to 2020: a cross-sectional study

Background

Hypertension is a prevalent cardiovascular risk factor that significantly contributes to morbidity and mortality worldwide. Previous studies have highlighted the role of inadequate sleep during weekdays in the development of hypertension. However, the potential mitigative effects of weekend catch-up sleep (WCS) on hypertension have been less explored.

Methods

This cross-sectional study analyzed data from the National Health and Nutrition Examination Survey (NHANES) 2017-2020, focusing on American adults. We assessed the association between WCS (defined as the difference in sleep duration between weekend and weekday) and the presence of hypertension. Participants were classified into two groups based on their WCS duration: none (below 1 hours), yes (over 1 hours). Multivariable logistic regression models adjusted for potential confounders such as age, gender, Body mass index (BMI), and lifestyle factors were utilized to explore this association. A Generalized Additive Model (GAM) was employed to generate smooth curves for a nuanced analysis of the nonlinear relationship.

Results

The findings indicated that moderate WCS (less than 4 hours) was significantly associated with a reduced risk of hypertension, while excessive WCS (greater than 4 hours) showed no significant protective benefits.

Conclusion

Moderate weekend catch-up sleep could serve as an effective intervention to mitigate hypertension risk, especially in populations with restricted weekday sleep. These results suggest the potential for integrating sleep management strategies into public health recommendations to address hypertension. Future longitudinal studies are needed to confirm these findings and clarify the mechanisms underlying the relationship between WCS and hypertension risk.

Sleep regularity in adolescents: Associations with sleep, rest-activity indices, and prospective substance use and depression

Sleep is important for adolescent development and has been linked to a variety of mental health difficulties. New research suggests that sleep irregularity may be more clinically relevant than relying on mean values. This study aimed to (1) quantify the relationship between the sleep regularity index (SRI), a novel parameter reflecting the probability that an individual will be in the same state [asleep or awake] 24 h apart, and other actigraphy-derived sleep and rest-activity metrics, (2) evaluate concurrent and prospective associations between the SRI and mental health symptoms (depressive symptoms and substance use), and (3) test sex as a moderator. At baseline, a community-based sample of adolescents (n = 295, 56.27% female, 58.98% White, age = 15.44) wore an actiwatch for 1 week to measure rest-activity rhythms and sleep-wake cycles. Actigraphy data were used to derive sleep metrics, SRI, and nonparametric rest-activity indices. Adolescents also completed self-report measures of substance use and depression at baseline and at 6-month follow-up. Partial correlations indicated that individuals with more sleep irregularity had less interdaily stability, less robust relative amplitude, lower sleep efficiency, shorter total sleep time, longer sleep onset latency, more social jetlag, and a later sleep midpoint. Regression analyses revealed that sleep irregularity was associated with a lifetime history of substance use, first-onset substance use, and a prospective increase in depressive symptoms, even after accounting for sleep duration and subjective sleep disturbances. The sleep regularity index may be a potential modifiable risk factor for enhancing adolescent mental health.

Night shift work and breast cancer risk - 2023 update of epidemiologic evidence

Introduction

Night shift work is a complex and frequent occupational exposure, and breast cancer stands as the most prevalent cancer in women. The International Agency for Research on Cancer (IARC) has twice classified night shift work as a probable breast carcinogen, with the latest classification in June 2019. Since that time, new epidemiologic data has emerged.

Methods

We searched PubMed for original articles based on cohort and case-control studies of "breast cancer and night shift work" published after the IARC evaluation in June 2019.

Results

In total six cohorts and four case-control studies were included in our review. Overall, we observed some support for associations between persistent (long duration or high frequency) night shift work and an increase in breast cancer risk, though most studies were relatively small and statistically under-powered. Moreover, the recent studies do not contribute further evidence regarding the interaction with menopausal status, diurnal preference, hormonal subtypes of breast cancer or gene-environment aspects, which were issues that were left from the IARC evaluation.

Conclusions

The available new results somewhat consolidate the epidemiological evidence from IARC's 2019 evaluation, and do not provide further evidence regarding interaction of interest, e.g. menopausal status, etc. Therefore, long term follow-up of prospective cohorts or nested case-control studies, including precise exposure assessment and examinations of relevant interactions such as menopausal status, diurnal preference, hormonal subtypes of breast cancer and gene-environment aspects, are warranted. Meanwhile, protective measures for the night workers should be considered.

Time for bed: diet, sleep and obesity in children and adults

Sufficient sleep is necessary for optimal health, daytime performance and wellbeing and the amount required is age-dependent and decreases across the lifespan. Sleep duration is usually affected by age and several different cultural, social, psychological, behavioural, pathophysiological and environmental factors. This review considers how much sleep children and adults need, why this is important, what the consequences are of insufficient sleep and how we can improve sleep. A lack of the recommended amount of sleep for a given age group has been shown to be associated with detrimental effects on health including effects on metabolism, endocrine function, immune function and haemostatic pathways. Obesity has increased worldwide in the last few decades and the WHO has now declared it a global epidemic. A lack of sleep is associated with an increased risk of obesity in children and adults, which may lead to future poor health outcomes. Data from studies in both children and adults suggest that the relationship between sleep and obesity may be mediated by several different mechanisms including alterations in appetite and satiety, sleep timing, circadian rhythm and energy balance. Moreover, there is evidence to suggest that improvements in sleep, in both children and adults, can be beneficial for weight management and diet and certain foods might be important to promote sleep. In conclusion this review demonstrates that there is a wide body of evidence to suggest that sleep and obesity are causally related and recommends that further research is required to inform policy, and societal change.

Sleep in People Experiencing Homelessness Under Different Conditions and Seasons

Poor sleep represents a central health disparity for people experiencing homelessness, and any intervention to alleviate the impacts of homelessness should aim to improve sleep. We measured actimetry-based sleep in homeless adults spending their nights in four types of shelters in Seattle, WA, during the summer and winter. Homeless participants experienced more sleepless nights than housed participants in both seasons. During the summer sleeping nights, homeless participants experienced sleep patterns similar to housed subjects, but during the winter, their sleep duration was up to 1.5 hours shorter. Similarly, sleep quality, determined through sleep variability index, activity during the night, and intraindividual variability of sleep parameters, was poorer during the winter in homeless than in housed participants. Our study demonstrates the feasibility of using objectively measured sleep as a proxy for assessing the value of specific interventions to improve living conditions in people experiencing homelessness. Given the bidirectional relationship between sleep and both physical and mental health, our study reveals the health inequities of chronic sleep disparity for those living outdoors.

Significance statement

Sleep disparities are central to the poor physical and mental health experienced by houseless people. Here we show that measured sleep through wrist actigraphy captures different aspects of this sleep disparity and represents a useful, objective metric of the impact of interventions to improve living conditions among people experiencing homelessness.

Discrepancies between subjective and objective sleep assessments revealed by in-home electroencephalography during real-world sleep

Sleep insufficiency and sleep disorders pose serious health challenges. This study aimed to determine the potential discrepancy between subjective and objective sleep assessments, including the latter made by physicians, by analyzing a 421-participant dataset in Japan comprising multiple nights of in-home sleep electroencephalogram (EEG) data and questionnaire responses on sleep habits or subjective experiences. We employed logistic regression models to examine which subjective and objective sleep parameters physicians are paying attention to when assessing sleep insufficiency, insomnia, sleep quality, and sleep apnea. Questionnaire responses, including subjective sleep assessments, exhibited poor performance predicting physicians' assessments, whereas objective data demonstrated good predictive performance, indicating a discrepancy between subjective and objective sleep assessments. Although the in-home sleep EEG measurements had minimal first night effects, incorporating measurements over multiple nights can improve the detection of objective insomnia. Moreover, we found that participants with severe sleep insufficiency overestimated their sleep duration, whereas those with subjective insomnia but without objective insomnia underestimated it. Additionally, subjective sleep quality reflected sleep efficiency but not the frequency of short awakenings or objective sleep depth. In particular, the effects of apnea on objective sleep quality were not subjectively perceived. Collectively, our findings suggest that subjective sleep assessments alone are insufficient for evaluating sleep health and that health checkups and advice based on sleep EEG measurements may be useful in improving sleep habits and for early detection of sleep disorders.

Specific Nutrients Mediate the Association of Food Insecurity and Sleep Regularity Index (SRI) in U.S. Adults: NHANES 2011-2014

BACKGROUND/OBJECTIVES

Food-insecure individuals are at risk for poor health outcomes, including substandard sleep health. A possible association of food insecurity with sleep regularity has not been explored, and factors contributing to the relationship between food insecurity and sleep are not well understood. This cross-sectional study explored the relationship between food insecurity and sleep regularity and identified specific nutrients that mediated the association.

METHODS

This study used dietary intake, interview, physical examination, actigraphy, and laboratory data from NHANES 2011-2014 to assess the possible correlation between food insecurity and sleep in a sample of U.S. adults (n = 6730). Mediation analysis was conducted to determine specific serum biomarkers and intake of nutrients that indirectly contributed to the relationship.

RESULTS

Food insecurity was negatively correlated with sleep regularity. Dietary intake of fiber; vitamins A, B1, B2, C, E, and K; β-carotene; zinc; copper; and potassium and serum concentrations of palmitoleic acid had significant indirect effects on this association. The low/marginal food security group under-consumed vitamin K, and the very low food security group under-consumed vitamin K and zinc. Among food-insecure, income-eligible adults, those who received benefits from food assistance programs consumed significantly less fiber and β-carotene and exhibited significantly higher serum concentrations of palmitoleic acid than non-participants.

CONCLUSIONS

Food insecurity predicted sleep regularity, and this relationship was mediated by dietary intake and serum concentrations of specific nutrients, underscoring the role of nutrition security when evaluating potential health impacts for adults experiencing food insecurity.

Sleep Capital: Linking Brain Health to Wellbeing and Economic Productivity Across the Lifespan

INTRODUCTION AND FRAMEWORK

Sleep capital contributes to individual and societal wellbeing, productivity, and economic outcomes and involves a novel aspect of brain capital. It encompasses the quality and quantity of sleep as integral components that influence cognitive abilities, mental and brain health, and physical health, affecting workplace productivity, learning, decision-making, and overall economic performance. Here, we bring a framework to understand the complex relationship between sleep quality, health, wellbeing, and economic productivity. Then we outline the multilevel impact of sleep on cognitive abilities, mental/brain health, and economic indicators, providing evidence for the substantial returns on investment in sleep health initiatives. Moreover, sleep capital is a key factor when considering brain health across the lifespan, especially for the aging population.

DISCUSSION

We propose specific elements and main variables to develop specific indexes of sleep capital to address its impacts on health, wellbeing and productivity.

CONCLUSION

Finally, we suggest policy recommendations, workplace interventions, and individual strategies to promote sleep health and brain capital. Investing in sleep capital is essential for fostering a healthier, happier, fairer and more productive society.

[Factors of depression according to actigraphy in the fall season]

OBJECTIVE

To evaluate the relationship between sleep parameters, physical activity, and illumination obtained by weekly actigraphy and depression symptoms measured by the Beck Depression Inventory (BDI-II) in young adults in the fall season.

MATERIAL AND METHODS

The crossover study, conducted during one fall month, included 122 adults (mean age 24.40 years, 76.6% females) from Tyumen (Russia). Participants were monitored for seven days using actigraphy and completed the Russian version of the BDI-II questionnaire to assess depressive symptoms. Actigraphy data were analyzed for quantitative and qualitative sleep parameters, dynamic illumination, and circadian rhythm of motor activity. Both mean values and regularity indicators were recorded. Statistical analysis was performed using linear and multiple linear regression methods, using the Benjamini-Hochberg procedure to control the incidence of false correlations associated with multiple testing.

RESULTS

The analysis showed significant correlations between various actigraphic indicators and the level of depression according to BDI-II. In particular, the BDI-II integral score was significantly associated with a decrease in the amplitude of the circadian rhythm of physical activity (PIM A: -0.258; p=0.005), a high instability of sleep efficiency (SL_EFF SD: -0.323; p=0.0003), a high standard deviation of the moment of awakening (WT SD: -0.258; p=0.005), a decrease in the inter-day stability of the activity rhythm (IS: -0.260; p=0.004), and a lower circadian light hygiene index (NA_bl: -0.193; p=0.036). After multiple comparison adjustments, low PIM A, reduced inter-day stability (IS), increased WT SD, and high SL_EFF SD remained significant predictors of depressive symptoms. In age-, sex-, and body mass index (BMI)-adjusted multiple regression, WT SD (β=-0.258; p=0.006), SL_EFF SD (β=-0.302; p=0.0006), and IS (β=-0.225; p=0.013) were significant factors.

CONCLUSION

The data obtained indicate a complex relationship between sleep dynamics and mental health in the context of BDI-II. They emphasize the critical importance of using parameters that assess sleep regularity as one of the markers of biological clock synchrony to increase informative value and improve the interpretation of data obtained using wearable devices.

The effect of rotator cuff repair on sleep quality: Influencing factors and the impact of narcotic medication on postoperative sleep patterns: A systematic review and meta-analysis

Background

Impaired sleep quality often drives patients with rotator cuff tears (RCT) to seek surgical intervention. This meta-analysis reviews the impact of arthroscopic rotator cuff repair (ARCR) on sleep quality beyond six months and identifies influencing factors, primarily narcotics, on sleep quality.

Methods

The search spanned PubMed, Google Scholar, Embase, and the Cochrane Central Register, targeting articles evaluating rotator cuff injury and sleep quality. Information gathered included study features, bias risk assessment, evaluation of sleep quality using sleep-specific patient-reported outcomes, and the effects of opiates on sleep outcomes.

Results

Ten studies, including 445 patients who underwent ARCR were included. The preoperative mean Pittsburgh Sleep Quality Index (PSQI) varied from 6.6 to 15. Eight studies presented a mean PSQI score of 3.6-7.1 at 6 months postoperatively; two studies reported mean score of 4.2 and 5.4 at 12 months. Both were found to be statistically significant by this meta-analysis compared to preoperative scores. Three studies found narcotic use, RCT size, alcohol consumption, diabetes, and hypertension to negatively affect PSQI scores.

Discussion

Arthroscopic rotator cuff repair significantly improves sleep quality at 6 and 12 months following surgery. Perioperative narcotic use, RCT size, alcohol consumption, diabetes, and hypertension may negatively impact sleep quality.

Sleep and hypertension - up to date 2024

People spend one-third of their lives sleeping, and adequate, restful sleep is an essential component of a healthy life. Conversely, disruption of sleep has been found to cause various physical and mental health problems. Emerging research has shown that blood pressure (BP) during sleep is a stronger predictor of cardiovascular events than conventional office BP or daytime BP. Thus, management of both sleep health and nighttime BP during sleep is important for preventing cardiovascular events. However, recent studies demonstrated that nighttime BP is poorly controlled compared with office BP and daytime BP. This finding is understandable, given the challenges in monitoring BP during sleep and the multiplicity of factors related to nocturnal hypertension and BP variability. This review summarizes recent evidence and considers future perspectives for the management of sleep and hypertension.

Mental health, substance use, and a composite of sleep health in adults, 2018 Ohio behavioral risk factor surveillance system

OBJECTIVES

Various factors impact sleep health including mental health and substance use. Mental health issues and substance use continue to rise in the United States. Yet, the association between mental health, substance use and sleep health in adults remains unclear.

METHODS

We used multivariable linear regression models to examine the associations between mental health (poor mental health days in the past 30 days) and substance use (marijuana, tobacco, alcohol) with sleep health (individual dimensions of sleep: alertness, sleep efficiency, duration, and sleep health composite score) in 4333 participants from the 2018 Ohio Behavioral Risk Factor Surveillance System Survey.

RESULTS

Better mental health was associated with higher alertness, higher sleep efficiency, longer sleep duration and a higher sleep health composite score even after controlling for covariates (individual: sex at birth, age, body mass index, race, education, sleep disordered breathing, and area-level: socioeconomic deprivation) (all p < .001). Higher marijuana and tobacco use were associated with lower individual sleep health dimensions (marijuana with sleep efficiency and duration and tobacco use with lower efficiency) and a lower sleep health composite score even after controlling for covariates for tobacco use (p < .001). Contrary to the hypothesis, higher alcohol use was associated with higher alertness and a higher sleep health composite score (p < .001), however after adjusting for covariates these associations were no longer significant.

CONCLUSIONS

The implications of these trends on sleep health are important to address as mental health and substance use are modifiable targets to consider when addressing sleep health.

Sleep Irregularity and the Incidence of Type 2 Diabetes: A Device-Based Prospective Study in Adults

OBJECTIVE

To prospectively examine the association between device-measured sleep regularity and incidence of type 2 diabetes (T2D) in a population-based sample of adults. We also examined if meeting sleep duration recommendations attenuated or eliminated the effects of irregular sleep on T2D.

RESEARCH DESIGN AND METHODS

We conducted a prospective cohort study of adults aged 40-79 years participating in the UK Biobank accelerometer substudy. Participants wore wrist-attached accelerometers for a duration of 7 days, which was used to compute the Sleep Regularity Index (SRI). Participants were categorized as irregular (SRI <71.6), moderately irregular (SRI between 71.6 and 87.3), and regular (SRI >87.3) sleepers. T2D diagnosis was obtained through self-reports and health records.

RESULTS

We analyzed data from 73,630 individuals observed for 8 years, without a history of T2D and without an event in the first year of follow-up. Compared with regular sleepers, irregular (hazard ratio [HR] 1.38; 95% CI 1.20-1.59) and moderately irregular sleepers (HR 1.35; 95% CI 1.19-1.53) were at higher risk of T2D incidence. Dose-response analyses treating SRI as a continuous measure showed higher T2D incidence with SRI scores <80. Meeting current sleep duration recommendations did not counteract the adverse effects of irregular (HR 1.35; 95% CI 1.09-1.66) or moderately irregular (HR 1.29; 95% CI 1.08-1.54) sleep on T2D incidence.

CONCLUSIONS

Moderate and high sleep irregularity were deleteriously associated with T2D risk, even in participants who slept ≥7 h per night. Future sleep interventions will need to pay more attention to consistency in bedtimes and wake-up times, in addition to sleep duration and quality.