Sleep Curtailment Research Articles

Melatonin ameliorates chronic sleep deprivation against memory encoding vulnerability: Involvement of synapse regulation via the mitochondrial-dependent redox homeostasis-induced autophagy inhibition

Voluntary sleep curtailment is increasingly more rampant in modern society and compromises healthy cognition, including memory, to varying degrees. However, whether memory encoding is impaired after chronic sleep deprivation (CSD) and the underlying molecular mechanisms involved remain unclear. Here, using the mice, we tested the impact of CSD on the encoding abilities of social recognition-dependent memory and object recognition-dependent memory. We found that memory encoding was indeed vulnerable to CSD, while memory retrieval remained unaffected. The hippocampal neurons of mice with memory encoding deficits exhibited significant synapse damage and hyperactive autophagy, which dissipates during regular sleep cycles. This excessive autophagy appeared to be triggered by damage to mitochondrial DNA (mtDNA), resulting from oxidative stress within the mitochondria. The relief at the behavioral and molecular biological levels can be achieved with intraperitoneal injections of the antioxidant compound melatonin. Moreover, our in vitro experiments using HT-22 cells demonstrated that oxidative stress induced by hydrogen peroxide led to oxidative damage, including mtDNA damage, and activation of autophagy. Melatonin treatment effectively countered these effects, restoring redox homeostasis and reducing excessive autophagic activity. Notably, this protective effect was not observed when melatonin was administered as a pre-treatment. Together, our findings reveal the vulnerability of memory encoding during chronic sleep curtailment, which is caused by oxidative stress and consequent enhancement of autophagy, suggest a potential therapeutic strategy for addressing these effects following prolonged wakefulness through melatonin intervention, and reiterate the significance of adequate sleep for memory formation and retention.

The Impact of Delayed School Start Times During COVID-19 on Academic Performance: A Longitudinal Naturalistic Study in Italian High Schools.

Delaying school start times has been proposed as a potential solution to address chronic sleep curtailment among adolescents and its negative consequences on their physical and mental well-being. This study investigates the impact of delayed school start times due to the COVID-19 pandemic on academic achievement. Two separate observational studies were conducted involving high school students from the first/second year (n=232) (Study 1) and from the final year (n=39) (Study 2). Multivariate Analyses of Covariance were performed to assess for statistical differences in academic performance (ie, global, humanistic, and scientific performance) and absenteeism (ie, number of school absences). Two main factors were considered: "school start time" (ie, standard-8:00 AM vs late-9:40 AM) and "time interval" (ie, first academic semester vs second academic semester), controlling for the school year (Study 1) and circadian preference (Study 2). Delaying school start times was positively associated with better academic performance in scientific subjects among first/second-year students (F1,229=6.083, p=0.026) and global academic performance among last-year students (F1,35=4.522, p=0.041). Furthermore, first/second-year students significantly increased their school achievement (F1,229>29.423, p<0.001) and school absences (F1,229=66.160, p<0.001) during the second semester of the academic year. No significant effect of "school start time" on school attendance was observed. Additionally, circadian preference was found to be a significant covariate among last-year students, with early chronotypes exhibiting better academic performance (r>0.369, p<0.025). These findings confirm past evidence about the beneficial effects of delayed school start times on academic outcomes, with the additional advantage of observing them within a natural context that emerged during the pandemic. Further research is needed to explore the phenomenon more systematically and take into account the broader implications of implementing this change.

P020 Exploring the Roles of Individual Rapid Eye Movement Sleep Parameters in Emotional Memory Processing

Abstract Background Maladaptive emotional memory processing is thought to underpin intrusion symptoms experienced by individuals with post-traumatic stress disorder (PTSD). Curtailment of rapid eye movement sleep (REMS) impairs emotional memory consolidation (EMC) and is proposed to contribute to the development of PTSD. However, the effects of altered REMS quality remain less explored. The present study aims to investigate the potential ability of REM percentage, REM latency, and REMS fragmentation to predict EMC. Methods The study forms part of a larger study investigating the effects of suvorexant and temazepam on REMS and EMC. Healthy participants view a series of emotionally positive, negative and neutral images, undergo overnight polysomnography with a study drug or placebo, and are assessed for recognition 48 hours after viewing the images. REMS architecture metrics are derived from polysomnographic data. EMC is calculated based on signal detection theory (d′ = z(hit rate) − z(false alarm rate)). Results Data collection is ongoing with 11 participants’ data being collected. A one-way ANOVA reveals a main effect of valence, with positive and negative images being recognised better than the neutral (p(positive-neutral) = .039, p(negative-neutral) = .039). REMS parameters do not significantly predict EMC when accounting for image valence, possibly due to low statistical power. Discussion Given existing literature supporting the contribution of REMS on emotional memory processing, promoting high-quality REMS may help facilitate adaptive EMC. Further data is required to examine this effect.

Sleep restriction by sleep timing late night or early wake: The impact on physical activity and dietary intake in adults

PurposeTo date, few studies have assessed whether the timing of sleep restriction impacts physical activity and energy intake patterns. Thus, we aimed to quantify physical activity and energy intake during an early wake (EW) and late sleep (LS) period. MethodsFourteen participants who met the inclusion criteria (sleep 7–9 h/night and a BMI of <40 kg/m2) participated in 3 crossover free-living conditions: normal sleep (NS, 7–9 h), EW (2-h early wake-time), and LS (2-h late to sleep) for 4 nights. Sleep duration (via Actiwatch), energy intake (via food diaries), and physical activity (via hip accelerometry) were recorded for 4 days/4 nights throughout each condition. ResultsSleep duration was reduced in both sleep restriction conditions compared to NS (p < 0.001) with no difference between sleep restriction conditions. Daily energy intake tended to increase in the LS condition (p = 0.056) but was unchanged during EW (p = 0.56). Fat (p = 0.031) and sodium (p = 0.039) intake were increased in the LS condition only compared to NS. During the EW condition, fat (p = 0.24) and sodium (p = 0.18) intake were not altered. No changes in carbohydrate or protein intake occurred between conditions. Daily steps tended to increase in the EW condition compared to NS (p = 0.058), while steps during the LS condition were unchanged (p = 0.28), with no differences between sleep restriction conditions. ConclusionThe timing of sleep curtailment differentially influences physical activity and EI the following day, such that EW results in increased physical activity, while LS leads to poorer dietary choices.

Wake-up ischemic stroke associated with short sleep duration and sleep behavior: A stratified analysis according to risk of obstructive sleep apnea

ObjectiveWake-up stroke (WUS) is an ischemic stroke occurring during nocturnal sleep with neurological deficits observed upon awakening. Our study aimed to investigate the association between WUS, sleep curtailment, and sleep behavior according to the obstructive sleep apnea (OSA) risk in patients with acute ischemic stroke. MethodsThis single-centered, retrospective study included hospitalized subjects with acute ischemic stroke occurring within 30 days. A total of 250 participants were classified as WUS or not and enquired about their sleep habits concerning sleep time on weekdays and weekends, demographic factors, and assessed comorbid medical conditions. Weekend catch-up sleep (CUS) was defined as the extension of sleep duration during weekends. The average weekly sleep duration and chronotype were assessed. The association between WUS and sleep factors was analyzed. ResultsWUS was observed in 70 patients (28.0%) with acute ischemic stroke. There were no significant differences in the demographic and stroke-related variables between the WUS and non-WUS (NWUS) groups. Upon stratified analysis based on risk of OSA, average weekly sleep duration (odds ratio, [OR] = 0.60, 95% confidence interval, [CI] = 0.41–0.89; p = 0.011), the presence of weekend CUS (OR = 0.07, 95% CI = 0.01–0.97; p = 0.047), and chronotype (OR = 0.62, 95% CI = 0.39–0.98; p = 0.041) were independently associated with WUS in low-risk group with OSA, but not in the high-risk group. ConclusionsShort sleep duration and lack of compensation are significantly associated with WUS in low-risk OSA group. Insufficient sleep and sleep behaviors could play a different role in causing ischemic stroke during sleep when patients are stratified by their risk of sleep apnea.

Two years after lockdown: Longitudinal trajectories of sleep disturbances and mental health over the COVID-19 pandemic, and the effects of age, gender and chronotype.

Since the first lockdown of Spring 2020, the COVID-19 contagion waves pervasively disrupted the sleep and mental health of the worldwide population. Notwithstanding the largest vaccination campaign in human history, the pandemic has continued to impact the everyday life of the general population for 2 years now. The present study provides the first evidence of the longitudinal trajectories of sleep disturbances and mental health throughout the pandemic in Italy, also describing the differential time course of age groups, genders and chronotypes. A total of 1062 Italians participated in a three-time-point longitudinal study covering two critical stages of the emergency (the first lockdown in April 2020 and the second partial lockdown in December 2020) and providing a long-term overview 2 years after the pandemic outbreak (April 2022). We administered validated questionnaires to evaluate sleep quality/habits, insomnia, depression, stress and anxiety symptoms. Analyses showed a gradual improvement in sleep disturbances, depression and anxiety. Conversely, sleep duration progressively decreased, particularly in evening-type and younger people. Participants reported substantial earlier bedtime and get-up time. Stress levels increased during December 2020 and then stabilised. This effect was stronger in the population groups apparently more resilient during the first lockdown (older people, men and morning-types). Our results describe a promising scenario 2 years after the pandemic onset. However, the improvements were relatively small, the perceived stress increased, and the re-establishment of pre-existing social/working dynamics led to general sleep curtailment. Further long-term monitoring is required to claim the end of the COVID-19 emergency on Italians' sleep and mental health.

Insufficient Sleep Syndrome: A Blind Spot in Our Vision of Healthy Sleep.

Chronic sleep deficiency (CSD) poses a threat to physical health, mental well-being, and social functioning. The concept of behaviorally induced CSD has not changed much since it was first introduced four decades ago. Behaviorally induced CSD is currently referred to as insufficient sleep syndrome (ISS). In the latest edition of the International Classification of Sleep Disorders (ICSD-3, 2014), ISS is considered a disorder of central hypersomnolence with diagnostic codes ICD-9-CM 307.44 and ICD-10-CM F51.12. In this review, we will describe the biological importance of sleep, the ramifications of CSD on the individual and society, the nosological status and diagnostic features of ISS, and the apparent lack of attention to ISS in contemporary medical practice and public health programs. The last three decades have seen a global rise in voluntary sleep curtailment such that ISS may already be the leading cause of CSD, not only in adults but also in school-aged children and adolescents. Acknowledging ISS as a public health priority is a necessary first step in our response to the global threat of CSD and CSD-related health consequences. It is only by confronting ISS directly that we can hope to develop and implement effective educational and advocacy programs, along with more responsible public health policies and regulations.

Xiaoyao Pill Improves the Affective Dysregulation of Sleep-deprived Female Mice by Inhibiting Brain Injury and Regulating the Content of Monoamine Neurotransmitter.

Sleep curtailment is a serious problem in many societies. Clinical evidence has shown that sleep deprivation is associated with mood dysregulation, formation of false memory, cardio-metabolic risk factors and outcomes, inflammatory disease risk, and all-cause mortality. The affective disorder dysregulation caused by insufficient sleep has become an increasingly serious health problem. However, to date, not much attention has been paid to the mild affective dysregulation caused by insufficient sleep, and there is no clear and standard therapeutic method to treat it. The Xiaoyao Pill is a classic Chinese medicinal formula, with the effect of dispersing stagnated hepatoqi, invigorating the spleen, and nourishing the blood. Therefore, it is most commonly used to treat gynecological diseases in China. In the present study, the effects of the Xiaoyao Pill on affective dysregulation of sleep-deprived mice and its underlying molecular mechanisms were investigated. Forty adult female mice were used in the present study. The sleep deprivation model was established by improving the multi-platform water environment method. After 7 consecutive days of sleep deprivation, the mice were administrated low (LXYP, 0.32mg/kg) and high (HXYP, 0.64 mg/kg) doses of the Xiaoyao Pill for two weeks. Then, the body weight, behavioral deficits, and histopathology were evaluated. Meanwhile, the expression of c-fos protein and the concentrations of monoamine neurotransmitters in the hippocampus and prefrontal cortex were determined after two weeks of treatment. Xiaoyao Pill treatment significantly increased body weight and sucrose consumption and decreased the irritability scores of the sleep-deprived mice. Meanwhile, Xiaoyao Pill treatment prevented brain injury and inhibited the expression of c-fos protein in the hippocampus and prefrontal cortex. In addition, HXYP treatment significantly upregulated the levels of NE in the hippocampus and prefrontal cortex (p < 0.01). LXYP treatment significantly up-regulated the levels of 5-HT in the prefrontal cortex. Meanwhile, both HXYP and LXYP treatment significantly upregulated the levels of DA in the prefrontal cortex (p < 0.05 or p < 0.01) of sleep-deprived mice. The present study demonstrates that Xiaoyao Pill treatment prevented the behavioral deficits of mice induced by sleep deprivation by promoting the recovery of brain tissue injury and up-regulating the levels of NE, 5-HT, and DA in the brain tissue.

Time to Consider the "Exposome Hypothesis" in the Development of the Obesity Pandemic.

The obesity epidemic shows no signs of abatement. Genetics and overnutrition together with a dramatic decline in physical activity are the alleged main causes for this pandemic. While they undoubtedly represent the main contributors to the obesity problem, they are not able to fully explain all cases and current trends. In this context, a body of knowledge related to exposure to as yet underappreciated obesogenic factors, which can be referred to as the “exposome”, merits detailed analysis. Contrarily to the genome, the “exposome” is subject to a great dynamism and variability, which unfolds throughout the individual’s lifetime. The development of precise ways of capturing the full exposure spectrum of a person is extraordinarily demanding. Data derived from epidemiological studies linking excess weight with elevated ambient temperatures, in utero, and intergenerational effects as well as epigenetics, microorganisms, microbiota, sleep curtailment, and endocrine disruptors, among others, suggests the possibility that they may work alone or synergistically as several alternative putative contributors to this global epidemic. This narrative review reports the available evidence on as yet underappreciated drivers of the obesity epidemic. Broadly based interventions are needed to better identify these drivers at the same time as stimulating reflection on the potential relevance of the “exposome” in the development and perpetuation of the obesity epidemic.

Effects of Experimental Sleep Restriction on Energy Intake, Energy Expenditure, and Visceral Obesity

BackgroundAlthough the consequences of sleep deficiency for obesity risk are increasingly apparent, experimental evidence is limited and there are no studies on body fat distribution. ObjectivesThe purpose of this study was to investigate the effects of experimentally-induced sleep curtailment in the setting of free access to food on energy intake, energy expenditure, and regional body composition. MethodsTwelve healthy, nonobese individuals (9 males, age range 19 to 39 years) completed a randomized, controlled, crossover, 21-day inpatient study comprising 4 days of acclimation, 14 days of experimental sleep restriction (4 hour sleep opportunity) or control sleep (9 hour sleep opportunity), and a 3-day recovery segment. Repeated measures of energy intake, energy expenditure, body weight, body composition, fat distribution and circulating biomarkers were acquired. ResultsWith sleep restriction vs control, participants consumed more calories (P = 0.015), increasing protein (P = 0.050) and fat intake (P = 0.046). Energy expenditure was unchanged (all P > 0.16). Participants gained significantly more weight when exposed to experimental sleep restriction than during control sleep (P = 0.008). While changes in total body fat did not differ between conditions (P = 0.710), total abdominal fat increased only during sleep restriction (P = 0.011), with significant increases evident in both subcutaneous and visceral abdominal fat depots (P = 0.047 and P = 0.042, respectively). ConclusionsSleep restriction combined with ad libitum food promotes excess energy intake without varying energy expenditure. Weight gain and particularly central accumulation of fat indicate that sleep loss predisposes to abdominal visceral obesity. (Sleep Restriction and Obesity; NCT01580761)

Sleep pattern regularity and measures of infant weight and length during the first 6 months

PurposeTo examine the association between sleep pattern regularity and measures of weight and length in infants. Design and methodsThis was a prospective observational study conducted in a university-affiliated children's hospital in northern Taiwan. A total of 316 healthy infants recruited during their 6-month well-child checkups had their weight and recumbent length measured, and wore an actigraph on the ankle for a week. Based on average weekday, weekend, and all-week sleep durations, infants were categorized into 3 groups: regular sleep, weekend catch-up sleep, and weekend sleep curtailment. General linear model analyses were performed with the 3 sleep regularity groups as the primary predictor variable of interest and infant anthropometry as the dependent variable. ResultsAt risk of overweight, overweight, and obese was present in a total of 62 (19.6%) infants. In both unadjusted and adjusted models, infants in the weekend catch-up sleep group (30.4%) and those in the weekend sleep curtailment group (34.5%) had significantly higher weight-to-length ratios, body mass index, weight-for-age z-scores, and weight velocity of 6-month increments z-scores when compared with infants in the regular sleep group (35.1%, all p < 0.05). ConclusionsDifferences in weekday-weekend sleep exist as early as in the first 6 months of life, and both catch-up sleep and sleep curtailment over the weekend is associated with higher measures of weight and length in infants. Practice implicationsSleep assessments in well-child checkups should include not only global assessments of average sleep duration but also address sleep patterns and their regularity.

Predicting vigilance vulnerability during 1 and 2 weeks of sleep restriction with baseline performance metrics.

We attempted to predict vigilance performance in adolescents during partial sleep deprivation using task summary metrics and drift diffusion modelling measures (DDM) derived from baseline vigilance performance. In the Need for Sleep studies, 57 adolescents (age = 15-19 years) underwent two baseline nights of 9-h time-in-bed (TIB), followed by two cycles of weekday sleep-restricted nights (5-h or 6.5-h TIB) and weekend recovery nights (9-h TIB). Vigilance was assessed daily with the Psychomotor Vigilance Task (PVT), with the number of lapses (response times ≥ 500 ms) as the primary outcome measure. The two DDM predictors were drift rate, which quantifies the speed of information accumulation and determines how quickly an individual derives a decision response, and non-decision time range, which indicates within-subject variation in physical, non-cognitive responding, e.g. motor actions. In the first week of sleep curtailment, faster accumulation of lapses was significantly associated with more lapses at baseline (p = .02), but not the two baseline DDM metrics: drift and non-decision time range (p > .07). On the other hand, faster accumulation of lapses and greater increment in reaction time variability from the first to the second week of sleep restriction were associated with lower drift (p < .007) at baseline. Among adolescents, baseline PVT lapses can predict inter-individual differences in vigilance vulnerability during 1 week of sleep restriction on weekdays, while drift more consistently predicts vulnerability during more weeks of sleep curtailment. Effects of Napping in Sleep-Restricted Adolescents, clinicaltrials.gov, NCT02838095. The Cognitive and Metabolic Effects of Sleep Restriction in Adolescents (NFS4), clinicaltrials.gov, NCT03333512.

Association of night-time sleep and day napping with the prevalence of MOSH in young obese men.

Obesity in men is also shown to be associated with reduced reproductive potential, and this particular subtype was described as male obesity-associated secondary hypogonadism (MOSH). Recent studies showing the influence of sleep disorders on testosterone levels suggested a potential role of sleep disorders in determining the development of MOSH. To assess the association between night-time sleep duration and day napping and the prevalence of MOSH. In this cross-sectional study, 226 obese male participants aged 18-30 years were enrolled. Daytime napping and night-time sleep duration data were collected using a standardized self-reported Chinese-language questionnaire. MOSH was defined as obese men (BMI ≥ 30kg/m2 ) with hypogonadal symptoms and decreased total testosterone level and/or free testosterone level, excluding other causes of hypogonadism. The overall prevalence of MOSH was 48.2% in this study. An inverse association was observed between night sleep duration and the risk of prevalent MOSH. Men who reported fewer than 6h of night-time sleep had reduced total testosterone and free testosterone levels and an increased risk of MOSH. Further regression analysis revealed that after adjustment for potential confounders, the odds ratio of MOSH for the short night-time sleep group (<6 h vs. 6-8 h) was 6.17 (p=0.040). No significant association was observed between day napping status and prevalence of MOSH. Short night sleep duration was associated with an increased risk of MOSH in the young obese Chinese population. Chronic sleep curtailment has a negative effect on obese men's health in terms of hypogonadism.

Acute Ramelteon Treatment Maintains the Cardiac Rhythms of Rats during Non-REM Sleep.

Sleep curtailment negatively affects cardiac activities and thus should be ameliorated by pharmacological methods. One of the therapeutic targets is melatonin receptors, which tune circadian rhythms. Ramelteon, a melatonin MT1/MT2 receptor agonist, has recently been developed to modulate sleep-wake rhythms. To date, the sleep-promoting effect of ramelteon has been widely delineated, but whether ramelteon treatment physiologically influences cardiac function is not well understood. To address this question, we recorded electrocardiograms, electromyograms, and electrocorticograms in the frontal cortex and the olfactory bulb of unrestrained rats treated with either ramelteon or vehicle. We detected vigilance states based on physiological measurements and analyzed cardiac and muscular activities. We found that during non-rapid eye movement (non-REM) sleep, heartrate variability was maintained by ramelteon treatment. Analysis of the electromyograms confirmed that neither microarousal during non-REM sleep nor the occupancy of phasic periods during REM sleep was altered by ramelteon. Our results indicate that ramelteon has a remedial effect on cardiac activity by keeping the heartrate variability and may reduce cardiac dysfunction during sleep.

Accumulation of sleep loss among shift-working truck drivers

ABSTRACT Sleep loss is known to contribute to road traffic accidents. Professional drivers are vulnerable to curtailment of sleep due to long driving bouts and shift work. To fill in the gap in the literature related to the buildup of sleep loss in irregular shift systems, we recorded the sleep and working hours of 47 shift-working long-haul truck drivers during a two-week period. Sleep (time in bed) was verified by actigraphy and sleep logs. Sleepiness was measured using the Karolinska Sleepiness Scale (KSS). Individual sleep need was based on self-assessments. We examined the accumulated sleep versus self-reported sleep need across the study period, using midnights as points of observation, and the accumulated sleep loss within 72 h prior to shift end (sleep versus need, SVN72). Across the study period, the drivers’ sleep was close to their self-reported sleep need, but 45% of the drivers showed accumulated sleep loss of >6 h at least once. SVN72 averaged −1.5 h and was 2.87 h shorter in connection with morning shifts compared to day or evening shifts. Night shifts showed no such difference. During days off, sleep exceeded sleep need by 1.13 h and was not dependent on the type of preceding work shift. SVN72 showed small-to-medium negative associations with on-duty KSS even after accounting for sleep within the 24 h prior to the shift end. Our results show that long-haul truck drivers are exposed to severe levels of accumulated sleep loss while working irregular shifts, but they can catch up on their lost sleep, especially during days off.

Abstract P048: A Model Of Chronic Insufficient Sleep Increases Markers Of Insulin Resistance In Postmenopausal But Not Premenopausal Women

Introduction: Insufficient sleep is widely prevalent among US adults and is a risk factor for type 2 diabetes (T2D). Experimental studies show adverse effects of acute, severe short sleep on insulin sensitivity, but it is unclear whether these reflect risks associated with milder short sleep routinely observed in the general population. To date, no study has evaluated the impact of prolonged mild sleep curtailment on markers of insulin resistance in women or whether these effects differ by menopausal status, known to impact insulin sensitivity. Hypothesis: Glucose and insulin levels, as well as a measure of insulin resistance (HOMA-IR), will increase during 6 wk of sleep restriction (SR) relative to adequate sleep (AS). Adverse effects of prolonged short sleep will be exacerbated in postmenopausal women. Methods: Thirty-four women (age: 38±14 y; BMI: 25.6±3.6 kg/m2; n=10 postmenopausal) with adequate habitual total sleep time (TST) (453±33 min) took part in a randomized crossover study with two 6-wk phases: AS and SR. In AS, participants were asked to maintain stable nightly bed and wake times determined from 2 wk of screening with wrist actigraphy and sleep logs. In SR, bedtime was delayed to reduce TST by approximately 1.5 h/night. Sleep was measured continuously using actigraphy and verified weekly for compliance. At wk 0, 3, 4, and 6 fasting blood samples were collected. Outcomes included glucose and insulin levels as well as HOMA-IR scores, calculated from those values. Linear-mixed models tested interactions of sleep condition with week on outcome measures in the full sample and by menopausal status. Results: Sleep condition impacted the change in TST from baseline (P&lt;0.0001), which was reduced in SR and unchanged in AS (-79±6 vs -4±6min). In the full sample, there was no sleep condition by week interactions for glucose (P=0.67), insulin (P=0.14), or HOMA-IR (P=0.16). Similar results were observed in premenopausal women (all P&gt;0.50). However, in postmenopausal women, there was a significant effect of sleep condition on change in insulin (P=0.046) and HOMA-IR (P=0.039) over the 6 wk. In SR, insulin (slope: 0.26±0.28 μU/mL) and HOMA-IR (slope: 0.07±0.08) increased, while AS resulted in reductions in these outcomes (insulin slope: -0.56±0.29 μU/mL; HOMA-IR slope: -0.16±0.08). Conclusions: We provide the first evidence that chronic short sleep, even if mild, adversely affects insulin sensitivity in postmenopausal women. In contrast, maintenance of AS may improve glycemic regulation. Interestingly, prolonged short sleep did not impact markers of insulin resistance in premenopausal women; further investigation into these life-stage related differences, including underlying mechanisms, is warranted. Results suggest that, in postmenopausal women, a group at heightened risk of poor sleep and T2D, achieving adequate sleep may be an effective strategy to improve cardiometabolic health.

Negative social jetlag - Special consideration of leisure activities and evidence from birdwatchers.

Birdwatching (birding) is a nature-based recreational activity, often including arising early in the morning. In the present study, we tested the effect of a negative social jetlag (SJL) in birders. Negative SJL implies that people have an even earlier sleep-wake rhythm on free days or weekends. As birds' activities start before or shortly after sunrise, especially during spring and early summer, birdwatchers follow this diurnal pattern. Further, birders are not homogeneous and vary greatly in recreational specialisation. The study was based on an online survey with 2,404 birdwatchers (55% male) who responded to questions about their sleep-wake times and about their birding activities. Birders show the same differences between weekdays and weekends/free days sleep like most other people. However, birdwatching days started earlier than weekdays (14min) and lasted longer. Thus, birdwatching days are shifted towards an earlier sleep-wake rhythm in total. Birdwatchers experience a sleep curtailment during birding. Instead of sleeping ~30min longer on weekends, they arise ~15min earlier, summing up to a sleep reduction of about ~45min compared to a regular weekend. The more psychologically committed birders are, the less they sleep, the earlier they arise, and the earlier is their midpoint of sleep on birdwatching days; meaning that highly specialised birders shift their sleep-wake rhythm to an earlier time compared to their regular weekend, and even their weekday sleep. Thus, birders may suffer more from the short- and long-term consequences of negative SJL. The results might stand representatively for other nature-related leisure activities.

598 Sleep Variability and Infant Anthropometry during the First 6 Months

Abstract Introduction Sleep plays a crucial role in children’s health and development, and emerging evidence suggests that sleep disturbances during infancy negatively impact both the neurocognitive and socioemotional outcomes later in life. However, no study has taken the variability of sleep into account when examining physical growth in infancy, which is a critical period for both healthy sleep and weight development. The purpose of the study was to examine the association between sleep variability and physical growth in infants aged 6 months. Methods 316 healthy infants recruited during their 6-month well-child checkups had their weight and length measured, and wore an actigraph on the ankle for a week. Average weekday, weekend, and all week sleep duration were computed, with infants categorized into three groups: regular sleep, weekend catch-up sleep, and weekend sleep curtailment. General linear model analyses were performed with sleep variability as the primary predictor variable of interest and infant anthropometry as the dependent variable. Results Average weekday daily sleep duration was 10.76 (1.06) hours which was similar to the average weekend daily sleep duration of 10.68 (1.06) hours. In both unadjusted and adjusted models controlling for potential confounding variables, infants in the weekend catch-up sleep group (30.4%) and those in the weekend sleep curtailment group (34.5%) had significantly higher weight-to-length ratios, body mass index, and weight-for-age z scores when compared with infants in the regular sleep group (35.1%, all p &amp;lt; 0.05). Conclusion Weekday-weekend sleep pattern differences exist even as early as in the first 6 months of life, and either weekend catch-up sleep or weekend sleep loss is associated with higher infant anthropometric markers. Our findings suggest that sleep assessments in infants in well-child checkups should include not only global assessments of average sleep duration but also address sleep pattern regularity. Support (if any) This study was funded by the National Health Research Institutes, Taiwan, NHRI-EX102-10229PC.

Efficacy of intermittent exposure to bright light for treating maladaptation to night work on a counterclockwise shift work rotation.

Objectives:Rotating shift work is associated with adverse outcomes due to circadian misalignment, sleep curtailment, work-family conflicts, and other factors. We tested a bright light countermeasure to enhance circadian adaptation on a counterclockwise rotation schedule.Methods:Twenty-nine adults (aged 20–40 years; 15 women) participated in a 4-week laboratory simulation with weekly counterclockwise transitions from day, to night, to evening, to day shifts. Each week consisted of five 8-hour workdays including psychomotor vigilance tests, two days off, designated 8-hour sleep episodes every day, and an assessment of circadian melatonin secretion. Participants were randomized to a treatment group (N=14), receiving intermittent bright light during work designed to facilitate circadian adaptation, or a control group (N=15) working in indoor light. Adaptation was measured by how much of the melatonin secretion episode overlapped with scheduled sleep timing.Results:On the last night shift, there was a greater overlap between melatonin secretion and scheduled sleep time in the treatment group [mean 4.90, standard deviation (SD) 2.8 hours] compared to the control group (2.62, SD 2.8 hours; P=0.002), with night shift adaptation strongly influenced by baseline melatonin timing (r2= -0.71, P=0.01). While the control group exhibited cognitive deficits on the last night shift, the treatment group’s cognitive deficits on the last night and evening shifts were minimized.Conclusions:In this laboratory setting, intermittent bright light during work hours enhanced adaptation to night work and subsequent readaptation to evening and day work. Light regimens scheduled to shift circadian timing should be tested in actual shift workers on counterclockwise schedules as a workplace intervention.

The effect of 5 nights of sleep restriction on empathic propensity

Literature supports the existence of a significant relationship between sleep quality/quantity and empathy. However, empathic ability and empathic propensity are distinct constructs. Expression of empathic propensity depends on the subjective cognitive costs attributed to the empathic experience. Studies on the effects of the experimental reduction in sleep duration on empathic behaviour are still lacking. Therefore, we investigated the consequences of 5 consecutive nights of sleep restriction on empathic propensity. A total of 42 university students (mean [SEM] age 24.09[0.65]years; 22 females) underwent a cross-over design consisting of 5 consecutive nights of regular sleep and 5 consecutive nights of sleep restriction with a maximum of 5hr sleep/night. After each condition, all participants were evaluated using the Empathy Selection Task, a new test assessing the motivated avoidance of empathy for its associated cognitive costs. The results showed different effects of sleep restriction depending on the habitual way of responding in the empathic context. Participants with baseline high levels of empathic propensity reduced their empathic propensity after prolonged sleep restriction. Differently, participants who tended to avoid empathising already in the habitual sleep condition maintained their empathic behaviour unchanged after sleep curtailment. In conclusion, inter-individual variability should be taken into account when evaluating the effects of sleep restriction on empathic propensity. People with habitual higher tendency to empathise could choose to avoid empathic experience following several consecutive nights of inadequate sleep.