Thermoregulation as a sleep signalling system

Cold sensitivity among female clinical nurses in Japan: A nationwide study

Objectives

This study aimed to clarify the nature of cold sensitivity in female nurses working in hospitals in Japan.

Design

A cross-sectional post survey research design.

Settings

The questionnaire targeted nurses working in 14 hospitals across ten prefectures throughout Japan.

Participants

1,138 female nurses.

Methods

The survey captured participants' characteristics, work environment, health, and lifestyle. The factors investigated were perceived cold sensitivity, cold sensitivity according to the Hiesho Sensation Scale, and cold sensitivity during nursing care. The Diagnostic Inventory of Health and Life Habits (DIHAL.2) assessed health and lifestyle habits.

Results

Of the respondents, 44.3 % were aware of daily cold sensitivity and 21.4 % had a cold sensitivity disorder. The majority of respondents (63.1 %) felt cold in their hands when providing nursing care, and 28.1 % felt discomfort due to the coldness of their hands. Individuals diagnosed with cold sensitivity disorders exhibited poorer overall health compared to those without such disorders. However, there was no statistically significant difference in the overall health status between individuals who reported perceiving cold sensitivity and those who did not. The group with perceived cold sensitivity had significantly lower scores on exercise behavior, meal regularity, rest, sleep regularity, and sleep sufficiency. The proportion of female nurses working in Japanese hospitals who experienced cold sensitivity was similar to that of Japanese women with the same sensitivity. Most female nurses experienced cold in their hands while providing care. Nearly 30 % of the respondents experienced discomfort owing to cold hands.

Conclusions

The study underscores the widespread issue of cold sensitivity among female nurses in Japanese hospitals, emphasizing the critical need for targeted interventions to improve their comfort and optimize care provision.

The interplay between sleep and ecophysiology, behaviour and responses to environmental change in fish

Evidence of behavioural sleep has been observed in every animal species studied to date, but current knowledge of the behaviour, neurophysiology and ecophysiology associated with sleep is concentrated on mammals and birds. Fish are a hugely diverse group that can offer novel insights into a variety of sleep-related behaviours across environments, but the ecophysiological relevance of sleep in fish has been largely overlooked. Here, we systematically reviewed the literature to assess the current breadth of knowledge on fish sleep, and surveyed the diverse physiological effects and behaviours associated with sleep. We also discuss possible ways in which unstudied external factors may alter sleep behaviours. For example, predation risk may alter sleep patterns, as has been shown in mammalian, avian and reptilian species. Other environmental factors - such as water temperature and oxygen availability - have the potential to alter sleep patterns in fish differently than for terrestrial endotherms. Understanding the ecological influences on sleep in fish is vital, as sleep deprivation has the potential to affect waking behaviour and fitness owing to cognitive and physiological impairments, possibly affecting ecological phenomena and sensitivity to environmental stressors in ways that have not been considered.

The relationship between daytime napping and glycemic control in people with type 2 diabetes

Aim

To examine the association between napping characteristics and glycemic control in people with type 2 diabetes.

Design

This study used a cross-sectional design.

Methods

A convenience sample of people with type 2 diabetes (N=226) were included. Glycemic control was indicated by HbA1c which was measured by A1C Now®+. Napping characteristics including napping frequency, duration, timing, and type were measured by validated questionnaires. Other variables, such as insomnia, cognitive impairment, and depression were measured by the Insomnia Severity Index, Montreal Cognitive Assessment, and Patient Health Questionnaire-9, respectively. Multivariate linear regression analyses were performed.

Results

The sample consisted of 122 women (54.0%), with a median age of 67 years. Their median HbA1c was 6.8%. No significant relationship was found between napping frequency and HbA1c. Among nappers, after controlling for covariates, long napping duration (≥60 min) and morning napping were both associated with poorer glycemic control. Compared with appetitive napping, restorative napping was associated with better glycemic control.

Conclusion

Daytime napping (e.g., duration and type) is an important modifiable factor for glycemic control in people with type 2 diabetes. This study provides new insights into the relationship between napping and glucose management among people with diabetes.

Lipopolysaccharide-Mediated Effects of the Microbiota on Sleep and Body Temperature

Background

Recent research suggests that microbial molecules translocated from the intestinal lumen into the host's internal environment may play a role in various physiological functions, including sleep. Previously, we identified that butyrate, a short-chain fatty acid, produced by intestinal bacteria, and lipoteichoic acid, a cell wall component of gram-positive bacteria induce sleep when their naturally occurring translocation is mimicked by direct delivery into the portal vein. Building upon these findings, we aimed to explore the sleep signaling potential of intraportally administered lipopolysaccharide, a primary component of gram-negative bacterial cell walls, in rats.

Results

Low dose of lipopolysaccharide (1 μg/kg) increased sleep duration and prolonged fever, without affecting systemic lipopolysaccharide levels. Interestingly, administering LPS systemically outside the portal region at a dose 20 times higher did not affect sleep, indicating a localized sensitivity within the hepatoportal region, encompassing the portal vein and liver, for the sleep and febrile effects of lipopolysaccharide. Furthermore, both the sleep- and fever-inducing effects of LPS were inhibited by indomethacin, a prostaglandin synthesis inhibitor, and replicated by intraportal administration of prostaglandin E2 or arachidonic acid, suggesting the involvement of the prostaglandin system in mediating these actions.

Conclusions

These findings underscore the dynamic influence of lipopolysaccharide in the hepatoportal region on sleep and fever mechanisms, contributing to a complex microbial molecular assembly that orchestrates communication between the intestinal microbiota and brain. Lipopolysaccharide is a physiological component of plasma in both the portal and extra-portal circulation, with its levels rising in response to everyday challenges like high-fat meals, moderate alcohol intake, sleep loss and psychological stress. The increased translocation of lipopolysaccharide under such conditions may account for their physiological impact in daily life, highlighting the intricate interplay between microbial molecules and host physiology.

Association of Abnormal Sleep Duration and Sleep Disturbance with Physical Activity in Older Adults: Between- and within-Person Effects

OBJECTIVES

Sleep is associated with physical activity (PA), yet the nature and directions of this association are less understood. This study aimed to disentangle the long-term temporal sequences between sleep duration/disturbance and PA in older adults, distinguishing between- and within-person effects.

DESIGN

Longitudinal panel study.

SETTING AND PARTICIPANTS

We conducted a longitudinal study using 3 waves of data collected in 2008/09 (T1), 2012/13 (T2), and 2016/17(T3) from adults aged ≥50 years in the English Longitudinal Study of Ageing (N = 10,749 individuals).

MEASURES

Sleep duration, sleep disturbance, and PA were assessed by self-reported questionnaires. We used cross-lagged panel models (CLPMs) to examine between-person effects and random intercept cross-lagged panel models (RI-CLPMs) to examine within-person effects.

RESULTS

Our analyses revealed a reciprocal relationship between abnormal sleep duration and low PA levels at between-person level (abnormal sleep duration to PA: βT1-T2 = -0.053, βT2-T3 = -0.058, all P < .001; PA to abnormal sleep duration: βT1-T2 = -0.040, βT2-T3 = -0.045, all P < .05), with abnormal sleep duration being the driving force in the dynamic association. In addition, there was a unidirectional effect of more severe sleep disturbance on lower levels of PA at both between- and within-person levels (between-person level: βT1-T2 = -0.032, βT2-T3 = -0.028, all P < .001; within-person level: βT1-T2 and T2-T3 = -0.031, all P = .011).

CONCLUSIONS AND IMPLICATIONS

This study adds novel insights into the temporal directionality of sleep and PA among community-dwelling older adults and highlights poor sleep as a potential risk factor for PA. Intervention strategies should aim to improve sleep to promote PA levels and successful aging.

Longitudinal genomic analyses of automatically-recorded vaginal temperature in lactating sows under heat stress conditions based on random regression models

BACKGROUND

Automatic and continuous recording of vaginal temperature (TV) using wearable sensors causes minimal disruptions to animal behavior and can generate data that enable the evaluation of temporal body temperature variation under heat stress (HS) conditions. However, the genetic basis of TV in lactating sows from a longitudinal perspective is still unknown. The objectives of this study were to define statistical models and estimate genetic parameters for TV in lactating sows using random regression models, and identify genomic regions and candidate genes associated with HS indicators derived from automatically-recorded TV.

RESULTS

Heritability estimates for TV ranged from 0.14 to 0.20 over time (throughout the day and measurement period) and from 0.09 to 0.18 along environmental gradients (EG, - 3.5 to 2.2, which correspond to dew point values from 14.87 to 28.19 ˚C). Repeatability estimates of TV over time and along EG ranged from 0.57 to 0.66 and from 0.54 to 0.77, respectively. TV measured from 12h00 to 16h00 had moderately high estimates of heritability (0.20) and repeatability (0.64), indicating that this period might be the most suitable for recording TV for genetic selection purposes. Significant genotype-by-environment interactions (GxE) were observed and the moderately high estimates of genetic correlations between pairs of extreme EG indicate potential re-ranking of selection candidates across EG. Two important genomic regions on chromosomes 10 (59.370-59.998 Mb) and16 (21.548-21.966 Mb) were identified. These regions harbor the genes CDC123, CAMK1d, SEC61A2, and NUDT5 that are associated with immunity, protein transport, and energy metabolism. Across the four time-periods, respectively 12, 13, 16, and 10 associated genomic regions across 14 chromosomes were identified for TV. For the three EG classes, respectively 18, 15, and 14 associated genomic windows were identified for TV, respectively. Each time-period and EG class had uniquely enriched genes with identified specific biological functions, including regulation of the nervous system, metabolism and hormone production.

CONCLUSIONS

TV is a heritable trait with substantial additive genetic variation and represents a promising indicator trait to select pigs for improved heat tolerance. Moderate GxE for TV exist, indicating potential re-ranking of selection candidates across EG. TV is a highly polygenic trait regulated by a complex interplay of physiological, cellular and behavioral mechanisms.

Sleep and global warming: How will we sleep when the Earth is hotter?

Societal concern about climate change and global warming has grown worldwide along with the concomitant awareness that health will be impacted deeply. Among living beings, humans have quite large capacities for adaptation to varied temperature conditions. Despite their tropical origin, they live under all Earth climates, such as polar, temperate, altitude, arid, and tropical climates, using a wide range of behavioral and physiological adaptive responses. We address the adaptive abilities of human sleep-wake regulation and its interplay with thermoregulation under different natural climates. Sleep represents one-third of our living time and is also a major determinant of morbidity and mortality; shortening sleep duration increases mortality and multimorbidity. In addition, major advances in sleep neurology have occurred in the last decades. Some have been extensively reviewed, notably comparative sleep physiology among animals, allowing one to hypothesize about the functions of the different sleep states, as well as their relation to cognitive neuroscience or body biorhythms. However, the question of the sleep adaptive capacity of humans to global warming has barely been addressed. We examine "normal" sleep and thermoregulation in young adults residing in temperate conditions. We then review the sleep and thermoregulatory reactions under various climatic conditions, demonstrating the role of sleep changes as potent adaptive responses to living under natural hot climatic conditions. As a result, we show that humans are well-equipped to adapt to severe climates.

Impact of Body Composition on Sleep and Its Relationship with Sleep Disorders: Current Insights

Sleep is involved in many physiological processes and is essential for both physical and mental health. Obesity and sleep deprivation due to sleep disorders are major public health issues. Their incidence is increasing, and they have a wide range of adverse health-related consequences, including life-threatening cardiovascular disease. The impact of sleep on obesity and body composition is well-known, and many studies have shown an association between insufficient or excessive sleep duration and obesity, body fat percentage, and weight gain. However, there is growing evidence of the effects of body composition on sleep and sleep disorders (particularly sleep disordered breathing) through anatomical and physiological mechanisms (nocturnal fluid shift, core body temperature, or diet). Although some research has been conducted on the bidirectional effects of sleep-disordered breathing and body composition, the specific effects of obesity and body composition on sleep and the underlying mechanisms that explain these effects remain unclear. Therefore, this review summarizes the findings on the effects of body composition on sleep and draws conclusions and proposals for future research in this field.

Deciphering local adaptation of native Indian cattle (Bos indicus) breeds using landscape genomics and in-silico prediction of deleterious SNP effects on protein structure and function

India has 50 registered breeds of native cattle (Bos indicus) which are locally adapted to diverse environmental conditions. This study aimed to investigate the genomic basis of adaptation of native Indian cattle and to predict the impact of key SNPs on the amino acid changes that affect protein function. The Illumina 777 K BovineHD BeadChip was used to genotype 178 native cattle belonging to contrasting landscapes and agro-climatic conditions. The genotype-environment association was investigated with R. SamBada, using 5,74,382 QC passed SNPs and 11 predictor variables (10 multi-collinearity controlled environmental variables and 1 variable as "score of PCA" on ancestry coefficients of individuals). In total, 1,12,780 models were selected as significant (q < 0.05) based on G score. The pathway ontology of the annotated genes revealed many important pathways and genes having a direct and indirect role in cold and hot adaptation. Only ten SNP variants had a SIFT score of < 0.05 (deleterious), and only two of them, each lying in the genes CRYBA1 and USP18, were predicted to be deleterious with high confidence. RaptorX predicted the tertiary structures of proteins encoded by wild and mutant variants of these genes. The quality of the models was determined using Ramachandran plots and RaptorX parameters, indicating that they are accurate. RaptorX and I-Mutant 2.0 softwares revealed significant differences among wild and mutant proteins. Adaptive alleles identified in the present investigation might be responsible for the local adaptation of these cattle breeds.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03493-3.

Sleep Pattern Analysis in Unconstrained and Unconscious State

Sleep accounts for one-third of an individual's life and is a measure of health. Both sleep time and quality are essential, and a person requires sound sleep to stay healthy. Generally, sleep patterns are influenced by genetic factors and differ among people. Therefore, analyzing whether individual sleep patterns guarantee sufficient sleep is necessary. Here, we aimed to acquire information regarding the sleep status of individuals in an unconstrained and unconscious state to consequently classify the sleep state. Accordingly, we collected data associated with the sleep status of individuals, such as frequency of tosses and turns, snoring, and body temperature, as well as environmental data, such as room temperature, humidity, illuminance, carbon dioxide concentration, and ambient noise. The sleep state was classified into two stages: nonrapid eye movement and rapid eye movement sleep, rather than the general four stages. Furthermore, to verify the validity of the sleep state classifications, we compared them with heart rate.

Bright Light Decreases Peripheral Skin Temperature in Healthy Men: A Forced Desynchrony Study Under Dim and Bright Light (II)

Human thermoregulation is strictly regulated by the preoptic area of the hypothalamus, which is directly influenced by the suprachiasmatic nucleus (SCN). The main input pathway of the SCN is light. Here, thermoregulatory effects of light were assessed in humans in a forced desynchrony (FD) design. The FD experiment was performed in dim light (DL, 6 lux) and bright white light (BL, 1300 lux) in 8 men in a semi-randomized within-subject design. A 4 × 18 h FD protocol (5 h sleep, 13 h wake) was applied, with continuous core body temperature (CBT) and skin temperature measurements at the forehead, clavicles, navel, palms, foot soles and toes. Skin temperature parameters indicated sleep-wake modulations as well as internal clock variations. All distal skin temperature parameters increased during sleep, when CBT decreased. Light significantly affected temperature levels during the wake phase, with decreased temperature measured at the forehead and toes and increased navel and clavicular skin temperatures. These effects persisted when the lights were turned off for sleep. Circadian amplitude of CBT and all skin temperature parameters decreased significantly during BL exposure. Circadian proximal skin temperatures cycled in phase with CBT, while distal skin temperatures cycled in anti-phase, confirming the idea that distal skin regions reflect heat dissipation and proximal regions approximate CBT. In general, we find that increased light intensity exposure may have decreased heat loss in humans, especially at times when the circadian system promotes sleep.

Dorsal clock networks drive temperature preference rhythms in Drosophila

Animals display a body temperature rhythm (BTR). Little is known about the mechanisms by which a rhythmic pattern of BTR is regulated and how body temperature is set at different times of the day. As small ectotherms, Drosophila exhibit a daily temperature preference rhythm (TPR), which generates BTR. Here, we demonstrate dorsal clock networks that play essential roles in TPR. Dorsal neurons 2 (DN2s) are the main clock for TPR. We find that DN2s and posterior DN1s (DN1ps) contact and the extent of contacts increases during the day and that the silencing of DN2s or DN1ps leads to a lower temperature preference. The data suggest that temporal control of the microcircuit from DN2s to DN1ps contributes to TPR regulation. We also identify anterior DN1s (DN1as) as another important clock for TPR. Thus, we show that the DN networks predominantly control TPR and determine both a rhythmic pattern and preferred temperatures.

The body temperature rhythm (BTR) is vital for maintaining homeostasis. Drosophila exhibit a daily temperature preference rhythm (TPR), which generates BTR. Chen et al. show that dorsal clock neurons in the brain form a time-dependent network and govern TPR by regulating a rhythmic pattern and a temperature setpoint.

Respective Impact of Day and Night Bed Baths on Critical Care Patients

BACKGROUND

Despite data supporting the reduction of interactions with patients during nighttime, bed bathing is sometimes performed within this period in sedated patients unable to manage their own hygiene care.

OBJECTIVES

To compare patient physiologic variables and adverse effect incidence between night and day bed baths.

METHODS

This was a single-center prospective observational study in a 12-bed intensive care unit during 2 months. Night period was defined to run from 10 pm to 6 am. Night bed baths were provided to sedated ventilated patients whatever their sedation, if their Richmond Agitation Sedation Scale score was -2 or deeper. Bed bath-induced changes in physiological variables, treatments, and related unscheduled events were registered during both night and day bed baths.

RESULTS

Twenty-one patients (aged 62.9 [52.5-73.2] years, 14 male patients) were included. We registered 97 night bed baths and 95 day bed baths. Heart rate increased only after day bed baths (85 beats/min [bpm] [69-97 bpm] vs 88 bpm [73-98 bpm], P = .02). Increase in Richmond Agitation Sedation Scale score occurred, respectively, during 13 (13.4%) and 8 (8.4%) night and day bed baths, without significant differences. Body temperature significantly decreased during both night and day bed baths (respectively, 37°C [36.6°C-37.4°C] vs 36.6°C [36.2°C-37.2°C], P < .0001; and 36.9°C [36.5°C-37.2°C] vs 36.7°C [36.2°C-37.2°C], P = .0006). Overall, unscheduled events, whether physiologic changes, pain, or calling a physician in rescue occurred in 97 procedures (50.5%), irrespective of their timing (night vs day, respectively 53% [54.6%] vs 44% [46.3%], P = .31).

DISCUSSION

Although unscheduled events occurred in half of bed baths, differences evidenced between nighttime and daytime bed baths were scarce. The appropriateness of nighttime bed bathing remains questionable.

Is It Time We Stop Discouraging Evening Physical Activity? New Real-World Evidence From 150,000 Nights

Professional and colloquial sleep hygiene guidelines advise against evening physical activity, despite meta-analyses of laboratory studies concluding that evening exercise does not impair sleep. This study is the first to investigate the association between objectively measured evening physical activity and sleep within a real-world big-data sample. A total of 153,154 nights from 12,638 individuals aged 18-60 years (M = 40.1 SD = 10.1; 44.5% female) were analyzed. Nighttime sleep and minutes of physical activity were assessed using Polar wearable devices for 14 consecutive days. Thirty minutes or more of moderate-to-near maximal physical activity during the 3 h before sleep onset were recorded in 12.4% of evenings, and were more frequent on weekdays than weekends (13.3 vs. 10.2% respectively, p < 0.001). Linear mixed modeling revealed that sleep efficiency was not significantly associated with evening physical activity, and that sleep duration was 3.4 min longer on average on nights following evenings in which participants engaged in 30 min or more of moderate-intense physical activity. Effects were found for sleep timing metrics, as evening physical activity was linked with earlier sleep onset and offset times (-13.7 and -9.3 min, respectively). Overall, these effects were greater- but still very small- on weekdays compared to weekends. The present study provides further evidence for the lack of meaningful links between sleep duration or quality and physical activity in the hours preceding sleep. Taken together with recent meta-analytic findings, these findings suggest that changes in public health recommendations are warranted regarding evening physical activity and its relation to sleep.

A randomized cross-over trial investigating differences in 24-h personal air and skin temperatures using wearable sensors between two climatologically contrasting settings

The influence of elevated air temperatures recorded in various urban microenvironments in adversely impacting biologically relevant disease end points has not yet been extensively tackled. This study is a post hoc analysis of the TEMP pilot trial, a randomized 2 × 2 cross-over trial that examined changes in metabolic and stress hormonal profiles of healthy adults in two settings (urban vs. rural) with distinctly different climatological characteristics during the Mediterranean summer. This analysis aimed to study the association between the 24-h personal air or skin temperature sensor measurements and the diary-based location type (indoors vs. outdoors) in urban (seaside) vs. rural (higher in altitude) microenvironments. Out of 41 eligible participants, a total of 37 participants were included in this post-hoc TEMP trial analysis. Wearable sensors recorded personal air temperature, skin temperature, and activity (as a surrogate marker of physical activity) in each setting, while a time-stamped personal diary recorded the types of indoor or outdoor activities. Temperature peaks during the 24-h sampling period were detected using a peak finding algorithm. Mixed effect logistic regression models were fitted for the odds of participant location (being indoors vs. outdoors) as a function of setting (urban vs. rural) and sensor-based personal temperature data (either raw temperature values or number of temperature peaks). During the study period (July-end of September), median [interquartile range, IQR] personal air temperature in the rural (higher altitude) settings was 1.5 °C lower than that in the urban settings (27.1 °C [25.4, 29.2] vs. 28.6 °C [27.1, 30.5], p < 0.001), being consistent with the Mediterranean climate. Median [IQR] personal air temperature in indoor (micro)environments was lower than those in outdoors (28.0 °C [26.4, 30.3] vs 28.5 °C [26.8, 30.7], p < 0.001). However, median [IQR] skin temperature was higher in indoor (micro)environments vs. outdoors (34.8 °C [34.0, 35.6] and 33.9 °C [32.9, 34.8], p < 0.001) and the number of both personal air and skin temperature peaks was higher indoors compared to outdoors (median [IQR] 3.0 [2.0,4.0] vs 1.0 [1.0,1.3], p < 0.007, for the skin sensors). A significant association between the number of temperature peaks and indoor location types was observed with either the personal air sensor (OR 3.1; 95% CI 1.2-8.2; p = 0.02) or the skin sensor (OR 3.7; 95% CI 1.4-9.9; p = 0.01), suggesting higher number of indoor air temperature fluctuations. Amidst the global climate crisis, more population health studies or personalized medicine approaches that utilize continuous tracking of individual-level air/skin temperatures in both indoor/outdoor locations would be warranted, if we were to better characterize the disease phenotype in response to climate change manifestations.

The relationship between body composition and sleep architecture in athletes

Sleep is essential for athletes to recover physical fitness. It has been suggested that sleep is affected by muscle volume. Compared to female athletes, male athletes with greater muscle volume may have inferior objective sleep quality. This study aimed to assess the relationship between body composition and objective sleep parameters in male and female athletes. The body composition of 17 male and 19 female collegiate athletes were measured, and they underwent overnight home sleep monitoring. Compared with female athletes, male athletes had more muscle mass and less fat mass. Moreover, male athletes had lower sleep efficiency, longer sleep onset latency, higher arousal index, less rapid eye movement (REM) sleep, and lower percentage of slow-wave (N3) sleep in the initial non-REM sleep. Furthermore, the percentage of muscle mass was inversely related, whereas fat mass or percentage of fat mass was directly related to the percentage of N3 sleep in the initial non-REM sleep. Overall, there were no significant association between sex and sleep parameters. However, a significant correlation was found within both subgroups. Objective sleep quality was suggested to be worse in male athletes than in female athletes, implying that sleep architecture may be related to the muscle volume.

Deconstructing Commercial Wearable Technology: Contributions toward Accurate and Free-Living Monitoring of Sleep

Despite prolific demands and sales, commercial sleep assessment is primarily limited by the inability to "measure" sleep itself; rather, secondary physiological signals are captured, combined, and subsequently classified as sleep or a specific sleep state. Using markedly different approaches compared with gold-standard polysomnography, wearable companies purporting to measure sleep have rapidly developed during recent decades. These devices are advertised to monitor sleep via sensors such as accelerometers, electrocardiography, photoplethysmography, and temperature, alone or in combination, to estimate sleep stage based upon physiological patterns. However, without regulatory oversight, this market has historically manufactured products of poor accuracy, and rarely with third-party validation. Specifically, these devices vary in their capacities to capture a signal of interest, process the signal, perform physiological calculations, and ultimately classify a state (sleep vs. wake) or sleep stage during a given time domain. Device performance depends largely on success in all the aforementioned requirements. Thus, this review provides context surrounding the complex hardware and software developed by wearable device companies in their attempts to estimate sleep-related phenomena, and outlines considerations and contributing factors for overall device success.

Presleep Arousal and Sleep in Early Childhood

Research suggests that arousal during the transition to sleep-presleep arousal-is associated with sleep disturbances. Although a robust literature has examined the role of presleep arousal in conferring risk for sleep disturbances in adults, substantially less research has examined the developmental origins of presleep arousal in early childhood. The authors examined presleep arousal using parent report and psychophysiological measures in a sample of preschoolers to explore the association between different measures of presleep arousal, and to examine how nightly presleep arousal is associated with sleep. Participants included 29 children assessed at 54 months of age. Presleep arousal was measured using parent reports of child arousal each night at bedtime and using a wearable device that took minute-by-minute recordings of heart rate, peripheral skin temperature, and electrodermal activity each night during the child's bedtime routine. This yielded a dataset with 4,550 min of ambulatory recordings across an average of 3.52 nights per child (SD = 1.84 nights per child; range = 1-8 nights). Sleep was estimated using actigraphy. Findings demonstrated an association between parent-reported and psychophysiological arousal, including heart rate, peripheral skin temperature, and skin conductance responses during the child's bedtime routine. Both the parent report and psychophysiological measures of presleep arousal showed some associations with poorer sleep, with the most robust associations occurring between presleep arousal and sleep onset latency. Behavioral and biological measures of hyperarousal at bedtime are associated with poorer sleep in young children. Findings provide early evidence of the utility of wearable devices for assessing individual differences in presleep arousal in early childhood.

Sleep disruption considerations for Paralympic athletes competing at Tokyo 2020

The role of sleep is now recognized as an important component for success in athletic performance, and sleep is proposed to be one of the most effective recovery strategies available. Insufficient sleep is commonly reported among athletes while several factors have been put forward to explain why elite athletes might experience poor sleep. However, Paralympic athletes may be predisposed to a greater risk of poor sleep due to the associated complexities of some impairment types. In fact, clinical research has previously shown that individuals with disabilities have a higher prevalence of sleep disturbances when compared to their able-bodied counterparts. However, research and evidence-based practices regarding the sleep of elite Paralympic athletes are limited. Firstly, this narrative review aims to identify challenges associated with the Paralympic games to obtain optimal sleep. Secondly, identify the specific risk factors to sleep associated with particular impairment groups within the Paralympic population, and lastly to propose potential sleep-enhancing strategies that might be of relevance for Paralympic athletes. From this review, initial observations have identified that Paralympic athletes may have a heightened risk of sleep-related problems, and importantly highlighted the current lack of understanding within this population group. Furthermore, this review identified where further research is warranted to better understand how specific impairments impact sleep and, consequently, athletic performance. Additionally, this review highlighted that the forthcoming Tokyo games may offer a unique challenge for athletes trying to obtain optimal sleep, due to the anticipated thermal demands and the consequent irregular scheduling of events.

COVID-19: Sleep, Circadian Rhythms and Immunity - Repurposing Drugs and Chronotherapeutics for SARS-CoV-2

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has affected nearly 28 million people in the United States and has caused more than five hundred thousand deaths as of February 21, 2021. As the novel coronavirus continues to take its toll in the United States and all across the globe, particularly among the elderly (>65 years), clinicians and translational researchers are taking a closer look at the nexus of sleep, circadian rhythms and immunity that may contribute toward a more severe coronavirus disease-19 (COVID-19). SARS-CoV-2-induced multi-organ failure affects both central and peripheral organs, causing increased mortality in the elderly. However, whether differences in sleep, circadian rhythms, and immunity between older and younger individuals contribute to the age-related differences in systemic dysregulation of target organs observed in SARS-CoV-2 infection remain largely unknown. Current literature demonstrates the emerging role of sleep, circadian rhythms, and immunity in the development of chronic pulmonary diseases and respiratory infections in human and mouse models. The exact mechanism underlying acute respiratory distress syndrome (ARDS) and other cardiopulmonary complications in elderly patients in combination with associated comorbidities remain unclear. Nevertheless, understanding the critical role of sleep, circadian clock dysfunction in target organs, and immune status of patients with SARS-CoV-2 may provide novel insights into possible therapies. Chronotherapy is an emerging concept that is gaining attention in sleep medicine. Accumulating evidence suggests that nearly half of all physiological functions follow a strict daily rhythm. However, healthcare professionals rarely take implementing timed-administration of drugs into consideration. In this review, we summarize recent findings directly relating to the contributing roles of sleep, circadian rhythms and immune response in modulating infectious disease processes, and integrate chronotherapy in the discussion of the potential drugs that can be repurposed to improve the treatment and management of COVID-19.

What Happened Pre- and during COVID-19 in South Korea? Comparing Physical Activity, Sleep Time, and Body Weight Status

The purpose of the current study is to investigate the changes in physical activity (PA), sleep time (ST), and body weight (BW) Pre- and during COVID-19 in South Korea, and specifically, PA data were obtained during COVID-19 at three-time points based on the multilevel social distancing policies. All data were surveyed by questionnaires online and offline, and participants were required to fill in the monthly average of daily step counts were recorded an application on participants’ smartphone devices from Pre-COVID-19 (2019 year) and during COVID-19 (2020 year). Participants were 834 adults (males: 54.4%, female: 45.6%) and all statistical analyses were summarized by SPSS 25.0 program. The monthly average of daily step counts was 6747.09 during Pre-COVID-19, but the PA during COVID-19 was 5812.11 daily step counts per month. Also, there were significant pairwise differences between average PA Pre-COVID-19 and each level of social distancing (p < 0.001). After COVID-19, the participants who slept less than 7 h decreased by 3.6%, while those who slept more than 9 h increased by that much. As a result of BW, 269 participants responded their BW changed during COVID-19, and 199 of them reported they gained BW during COVID-19 (74.0%). Although self-reported questionnaires may have led to an under-or over-estimation of ST and BW, the present study found that the environment in which the COVID-19 is prevalent had adverse relationships on PA, ST, and BW. Therefore, it is important to identify strategies to motivate individuals for remaining physically active and getting adequate sleep while maintaining social distancing due to the presence of the COVID-19 global pandemic.

High and low ambient temperature at night and the prescription of hypnotics

STUDY OBJECTIVES

This study investigated the association between ambient nighttime temperature and sleep problems assessed by the prescription dose of sleeping pills in South Korean adults.

METHODS

We used the 2002-2015 National Health Insurance Service-National Sample Cohort. A total of 711,079 adults who were 20 years old or older were included, wherein 42,858 adults (~6%) had been prescribed hypnotic medications including zolpidem (N05CF02) and triazolam (N05CD05). Ambient temperature data was calculated as the mean highest temperature of nighttime (23:00-07:00) for every month from January to December. We combined the drug-prescribed date with the administrative districts-level daily nighttime temperature between 2002 and 2015.

RESULTS

We found that a non-linear, U-shaped relationship between nighttime temperature and hypnotic medication prescription. With an increase per 1°C temperature or an increase in a square per 1°C, the prescription dose of sleeping pills was significantly increased (both p < 0.05). At each 5°C nighttime temperature, subjects belonging to low (≤0°C and 0-5°C) or high (20-25°C and ≥25°C) temperature categories had significantly higher doses of sleeping pills than those at the reference temperature (10-15°C). Changes in nighttime temperature had a significant non-linear effect on the prescribed dosage of hypnotic medications for both adults (p < 0.0001) and the elderly (p = 0.0006).

CONCLUSION

We found that either a high or low nighttime temperature was significantly associated with a high daily dose of hypnotic medications in the Korean population.

The effects of seasons and weather on sleep patterns measured through longitudinal multimodal sensing

Previous studies of seasonal effects on sleep have yielded unclear results, likely due to methodological differences and limitations in data size and/or quality. We measured the sleep habits of 216 individuals across the U.S. over four seasons for slightly over a year using objective, continuous, and unobtrusive measures of sleep and local weather. In addition, we controlled for demographics and trait-like constructs previously identified to correlate with sleep behavior. We investigated seasonal and weather effects of sleep duration, bedtime, and wake time. We found several small but statistically significant effects of seasonal and weather effects on sleep patterns. We observe the strongest seasonal effects for wake time and sleep duration, especially during the spring season: wake times are earlier, and sleep duration decreases (compared to the reference season winter). Sleep duration also modestly decreases when day lengths get longer (between the winter and summer solstice). Bedtimes and wake times tend to be slightly later as outdoor temperature increases.

Thermoregulation and Sleep: Functional Interaction and Central Nervous Control

Each of the wake-sleep states is characterized by specific changes in autonomic activity and bodily functions. The goal of such changes is not always clear. During non-rapid eye movement (NREM) sleep, the autonomic outflow and the activity of the endocrine system, the respiratory system, the cardiovascular system, and the thermoregulatory system seem to be directed at increasing energy saving. During rapid eye movement (REM) sleep, the goal of the specific autonomic and regulatory changes is unclear, since a large instability of autonomic activity and cardiorespiratory function is observed in concomitance with thermoregulatory changes, which are apparently non-functional to thermal homeostasis. Reciprocally, the activation of thermoregulatory responses under thermal challenges interferes with sleep occurrence. Such a double-edged and reciprocal interaction between sleep and thermoregulation may be favored by the fact that the central network controlling sleep overlaps in several parts with the central network controlling thermoregulation. The understanding of the central mechanism behind the interaction between sleep and thermoregulation may help to understand the functionality of thermoregulatory sleep-related changes and, ultimately, the function(s) of sleep. © 2021 American Physiological Society. Compr Physiol 11:1591-1604, 2021.

The effects of residential environment on the condition and fitness of soccer players in the summer

Exercise performance is reduced in hot environments due to physiological responses caused by increased body temperature. A proper residential environment is important for improving the performance and maintaining physical condition of soccer players in the summer. The purpose of this study was to determine the effect of indoor temperature of the resting space during the summer on the fitness and condition of soccer players. A total of 12 K-3 League semiprofessional players without serious injuries in the last 3 months voluntarily participated in the study. Participants performed speed (10 m, 20 m, and 30 m), soccer-specific coordination skill (dribbling), agility, repeated sprints, Yo-Yo intermittent level 2, vertical jump, and questionnaire (fatigue, sleep quality, muscle soreness, stress, and mood) after staying indoor temperature at 20°C, 26°C, and 30°C for one night, respectively. There was no difference among groups in physical fitness (speed, agility, jump, coordination, Yo-Yo intermittent level 2, and repeated sprints). The differences in fatigue and sleep quality were not statistically significant among groups, but they tended to be different. Muscle soreness was similar among all groups. Significant differences were observed between the 20°C and 30°C groups in stress and mood levels. The present study concluded that, while the physical fitness did not differ among groups, the 30°C residential environment was shown to have a negative psychological effect. Considering that many diseases associated with hot weather occur in low residential temperatures, a room temperature of 26°C is recommended for elite soccer players in hot summer weather.

Top 10 evidence-based countermeasures for night shift workers

Emergency edicine providers are responsible for ensuring the emergency department is staffed 24 hours a day. As such, providers must efficiently transition between day, swing and night shift on an almost weekly basis. There is no formal education in medical school or residency on how to approach the transition to and from night shift, remain alert and productive and maximise sleep during the day. There are a multitude of blogs and online sources discussing night shift, but few, if any, provide an evidence-based approach. This article will provide the top 10 evidence-based recommendations to increase sleep, maximise performance, decrease fatigue on shift and improve quality of life outside the workplace.

Effects of sound environment on the sleep of college students in China

Chinese college students reside primarily in four-person bedrooms and even six-person bedrooms, where the sound from roommates may affect their sleep. Therefore, the purpose of the present study is to investigate the effects of different sound sources and sound levels on sleep for college students in China. Based on sleep quality measurements, acoustic environment measurements, and a questionnaire survey with 90 participants in a typical residence hall in Harbin city, China, the results are as following: First, 68.89% of college students experienced sleep deprivation, and indoor noise was the most influential environmental factor among 15 disruptors that disturbed 50% of college students. Second, the number of occupants per room was a significant factor affecting the background sound level of sleep, which was highest when the number of occupants was two, and lowest when the number was five. Third, deep sleep time and rapid eye movements (REM) sleep time decreased 1.7 min and 1.4 min per 1 dBA (decibel with A-weight), with R² = 0.352 and 0.332, respectively (p < .001). In terms of the effect of sound sources on sleep, sleep was mostly disturbed by roommate conversation (77.42%), and noise caused by roommate sleep-related activities was the most common source of activities (67.74%). The present study can provide guidelines to help enhance the sleep quality of Chinese college students through improvements in the sound environment.

Still too noisy - An audit of sleep quality in trauma and orthopaedic patients

INTRODUCTION

An adequate amount of sleep is fundamental to health and well-being, especially for individuals recovering from an illness or injury. Trauma patients sustain musculoskeletal and tissue injuries and require a sufficient amount of sleep to promote recovery. However, it is known that patients can face difficulties sleeping in hospitals which impacts on their recovery.

AIM

To determine the quality of sleep, influence of sleep quality and the impact of sleep quality on recovery in trauma and orthopaedic patients.

METHODOLOGY

An exploratory descriptive design was applied using a clinical audit. As no standardised sleep assessment tool was identified, a sleep audit tool was developed.

FINDINGS

A total of 40 patients were recruited from two trauma and orthopaedic wards from a London Hospital in the United Kingdom. Of these 17 patients (43%) rated the quality of sleep as 'poor' and nearly half (n = 19, 46%) reported that the quality of their night-time sleep had affected their recovery. Two-thirds of patients reported noise was the main factor that disrupted their sleep, making it the highest contributing sleep disruptor (n = 26, 65%).

CONCLUSION

A significant association between poor quality of sleep and patient recovery was identified in this small sample of trauma and orthopaedic patients. The findings suggest that nurses should try to create a suitable sleeping environment to enhance patient recovery. There is a need for a standardised sleep assessment tool and sleep audit tool so that the quality of patients' sleep can be accurately assessed and documented.

Nicotinic acid promotes sleep through prostaglandin synthesis in mice

Nicotinic acid has been used for decades for its antiatherogenic properties in humans. Its actions on lipid metabolism intersect with multiple sleep regulatory mechanisms, but its effects on sleep have never been documented. For the first time, we investigated the effects of acute systemic administration of nicotinic acid on sleep in mice. Intraperitoneal and oral gavage administration of nicotinic acid elicited robust increases in non-rapid-eye movement sleep (NREMS) and decreases in body temperature, energy expenditure and food intake. Preventing hypothermia did not affect its sleep-inducing actions suggesting that altered sleep is not secondary to decreased body temperature. Systemic administration of nicotinamide, a conversion product of nicotinic acid, did not affect sleep amounts and body temperature, indicating that it is not nicotinamide that underlies these actions. Systemic administration of monomethyl fumarate, another agonist of the nicotinic acid receptor GPR109A, fully recapitulated the somnogenic and thermoregulatory effects of nicotinic acid suggesting that they are mediated by the GPR109A receptor. The cyclooxygenase inhibitor indomethacin completely abolished the effects of nicotinic acid indicating that prostaglandins play a key role in mediating the sleep and thermoregulatory responses of nicotinic acid.

Sex differences in factors associated with poor subjective sleep quality in athletes

BACKGROUND

Sleep is an important recovery period for athletes. In general, women are not satisfied with their sleep quality, which is also true for female soccer players, although the reasons remain to be elucidated. This study aimed to confirm sex difference in sleep quality among athletes from various fields of sport, and to investigate factors related to poor subjective sleep quality in male and female athletes.

METHODS

We collected data concerning subjective sleep quality, measured by Pittsburgh Sleep Quality Index (PSQI), from athletes who were 16 to 40 years of age and played various types of sports. Data concerning their sports, lifestyle, and sleep issues and sleep environments, and also menstrual issues for females, were collected.

RESULTS

Data from 207 male athletes and 215 female athletes were assessed. Among them, 31.4% of men and 48.8% of women had poor subjective sleep quality (i.e., PSQI≥6). In male athletes, witnessed apnea, episodes of disorientation or confusion during the time of sleep, long time gap between dinner and bedtime, and turning on the heating in the winter, were identified as factors associated with poor sleep quality by multivariate analysis, whereas in female athletes, bathing close to bedtime, habitual drinking, and being annoyed by noises at bedtime were identified.

CONCLUSIONS

In both populations, females had poorer subjective sleep quality than males. Sex differences exist in factors associated with poor subjective sleep quality. Thus, different approaches should be considered to improve their sleep quality.

The bidirectional association between physical activity and sleep in middle-aged and older adults: a prospective study based on polysomnography

Study Objectives

To examine the bidirectional association between physical activity (PA) and polysomnographically (PSG)-assessed sleep parameters characterized by total sleep time (TST), sleep onset latency (SOL), wake time after sleep onset (WASO), sleep efficiency and percentage of TST in N1, N2, and N3 stages and rapid eye movement (REM) sleep in middle-aged and older adults.

Methods

Longitudinal study based on a subsample of the Wisconsin Sleep Cohort. Self-reported PA information was used to estimate the metabolic equivalents of task (MET-minutes/week) activity and in-laboratory PSG exams provided information on sleep parameters at baseline and after 3-11 years of follow-up between 2004 and 2015. Poisson and linear regression models controlling for confounders estimated associations of sleep outcomes with changes in PA.

Results

A total of 424 participants (45.8% female; mean ± SD age 60.1 ± 7.5 years) were followed over an average of 5.0 ± 1.6 years. Compared to baseline PA of <500 MET-minutes/week (reference category), 500 to 1500 MET-minutes/week of PA was associated with lower incidences of TST <6 hours (relative risk, RR: 0.49; 95% confidence interval, CI: 0.27; 0.88), WASO >60 minutes (RR: 0.58; 95% CI: 0.41; 0.82) and sleep efficiency <80% (RR: 0.61; 95% CI: 0.39; 0.94), adjusting for sociodemographic, health behaviors and medical conditions. No significant associations were observed between baseline sleep characteristics and changes in PA through the follow-up.

Conclusion

In this prospective study, an intermediate level of PA at baseline predicted lower risk of incident short sleep time, higher WASO and lower sleep efficiency measured with PSG.

Feature Extraction and Evaluation for Driver Drowsiness Detection Based on Thermoregulation

Numerous reports state that drowsiness is one of the major factors affecting driving performance and resulting in traffic accidents. In the past, methods to detect driver drowsiness have been developed based on physiological, behavioral, and vehicular features. In this pilot study, we test the use of a new set of features for detecting driver drowsiness based on physiological changes related to thermoregulation. Nineteen participants successfully performed a driving simulation, while the temperature of the nose (Tnose) and wrist (Twrist) as well as the heart rate (HR) were monitored. On average, an initial increase in temperature followed by a gradual decrease was observed in drivers who experienced drowsiness. For non-drowsy drivers, no such trends were observed. In addition, HR decreased on average in both groups, yet the decrease in the drowsy group was more distinct. Next, a classification based on each of these variables resulted in an accuracy of 68.4%, 88.9%, and 70.6% for Tnose, Twrist, and HR, respectively. Combining the information of all variables resulted in an accuracy of 89.5%, meaning that ultimately the state of 17 out of 19 drivers was detected correctly. Hence, we conclude that the use of physiological features related to thermoregulation shows potential for future research in this field.

Butyrate, a metabolite of intestinal bacteria, enhances sleep

Emerging evidence suggests that the intestinal microbiota is a source of sleep-promoting signals. Bacterial metabolites and components of the bacterial cell wall are likely to provide important links between the intestinal commensal flora and sleep-generating mechanisms in the brain. Butyrate is a short-chain fatty acid produced by the intestinal bacteria by the fermentation of nondigestible polysaccharides. We tested the hypothesis that butyrate may serve as a bacterial-derived sleep-promoting signal. Oral gavage administration of tributyrin, a butyrate pro-drug, elicited an almost 50% increase in non-rapid-eye movement sleep (NREMS) in mice for 4 hours after the treatment. Similarly, intraportal injection of butyrate led to prompt and robust increases in NREMS in rats. In the first 6 hours after the butyrate injection, NREMS increased by 70%. Both the oral and intraportal administration of butyrate led to a significant drop in body temperature. Systemic subcutaneous or intraperitoneal injection of butyrate did not have any significant effect on sleep or body temperature. The results suggest that the sleep-inducing effects of butyrate are mediated by a sensory mechanism located in the liver and/or in the portal vein wall. Hepatoportal butyrate-sensitive mechanisms may play a role in sleep modulation by the intestinal microbiota.

Drosophila Temperature Preference Rhythms: An Innovative Model to Understand Body Temperature Rhythms

Human body temperature increases during wakefulness and decreases during sleep. The body temperature rhythm (BTR) is a robust output of the circadian clock and is fundamental for maintaining homeostasis, such as generating metabolic energy and sleep, as well as entraining peripheral clocks in mammals. However, the mechanisms that regulate BTR are largely unknown. Drosophila are ectotherms, and their body temperatures are close to ambient temperature; therefore, flies select a preferred environmental temperature to set their body temperature. We identified a novel circadian output, the temperature preference rhythm (TPR), in which the preferred temperature in flies increases during the day and decreases at night. TPR, thereby, produces a daily BTR. We found that fly TPR shares many features with mammalian BTR. We demonstrated that diuretic hormone 31 receptor (DH31R) mediates Drosophila TPR and that the closest mouse homolog of DH31R, calcitonin receptor (Calcr), is essential for mice BTR. Importantly, both TPR and BTR are regulated in a distinct manner from locomotor activity rhythms, and neither DH31R nor Calcr regulates locomotor activity rhythms. Our findings suggest that DH31R/Calcr is an ancient and specific mediator of BTR. Thus, understanding fly TPR will provide fundamental insights into the molecular and neural mechanisms that control BTR in mammals.

Sleep Depth Enhancement Through Ambient Temperature Manipulation in Mice

The restorative properties of deep sleep and its central role in learning and memory are well-recognized but still in the process of being elucidated with the help of animal models. Currently available approaches for deep sleep enhancement are mainly pharmacological and may have undesirable side effects on physiology and behavior. Here, we propose a simple strategy for sleep depth enhancement that involves manipulation of ambient temperature (Ta) using a closed-loop control system. Even mild shifts in Ta are known to evoke thermoregulatory responses that alter sleep-wake dynamics. In our experiments, mice evinced greater proportions of deep NREM sleep as well as REM sleep under the dynamic sleep depth modulation protocol compared to a reference baseline in which Ta was left unchanged. The active manipulation approach taken in this study could be used as a more natural means for enhancing deep sleep in patients with disorders like epilepsy, Alzheimer's disease and Parkinson's, in which poor quality sleep is common and associated with adverse outcomes.

Sleep environments and sleep physiology: A review

Sleep loss impairs task performance and post-physical activity recovery, cognitive performance and mood, heightens fatigue and decreases vigour; poor sleep quality impairs decision-making, the speed and accuracy of task performance, and post-exercise recovery. Sleep time and quality are affected by age, psychological and physiological conditions, culture and environmental factors. Skin temperature, rapid temperature change and sweating during sleep can significantly reduce sleep quality. Hence, the thermal properties of bedding and sleepwear, both in steady-state and transient ambient temperature conditions, are logically important factors. Research to date on sleeping thermal microclimates and their effect on sleep quality is scarce. This present review covers the fundamental elements of human sleep, highlighting physically active people, such as athletes, and the influence of sleepwear and bedding on sleep thermal microclimates, as well as the research methods that have been and could be used in this field. This review identifies opportunity for future research direction and approaches to understanding thermal environments that may support better human sleep.

Exercise can improve sleep quality: a systematic review and meta-analysis

Background

Insomnia is common. However, no systematic reviews have examined the effect of exercise on patients with primary and secondary insomnia, defined as both sleep disruption and daytime impairment. This systematic review and meta-analysis aimed to examine the effectiveness/efficacy of exercise in patients with insomnia.

Methods

We searched the Cochrane Central Register of Controlled Trials, MEDLINE, Embase, PsycINFO, World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov to identify all randomized controlled trials that examined the effects of exercise on various sleep parameters in patients with insomnia. All participants were diagnosed with insomnia, using standard diagnostic criteria or predetermined criteria and standard measures. Data on outcome measures were subjected to meta-analyses using random-effects models. The Cochrane Risk of Bias Tool and Grading of Recommendations, Assessment, Development, and Evaluation approach were used to assess the quality of the individual studies and the body of evidence, respectively.

Results

We included nine studies with a total of 557 participants. According to the Pittsburgh Sleep Quality Index (mean difference [MD], 2.87 points lower in the intervention group; 95% confidence interval [CI], 3.95 points lower to 1.79 points lower; low-quality evidence) and the Insomnia Severity Index (MD, 3.22 points lower in the intervention group; 95% CI, 5.36 points lower to 1.07 points lower; very low-quality evidence), exercise was beneficial. However, exercise interventions were not associated with improved sleep efficiency (MD, 0.56% lower in the intervention group; 95% CI, 3.42% lower to 2.31% higher; moderate-quality evidence). Only four studies noted adverse effects. Most studies had a high or unclear risk of selection bias.

Discussion

Our findings suggest that exercise can improve sleep quality without notable adverse effects. Most trials had a high risk of selection bias. Higher quality research is needed.

Calcitonin receptors are ancient modulators for rhythms of preferential temperature in insects and body temperature in mammals

Goda et al. provide molecular evidence that body temperature rhythm (BTR) is regulated distinctly from locomotor activity rhythms and show that diuretic hormone 31 receptor/calcitonin receptor is an ancient specific mediator of BTR during the active phase in organisms ranging from ectotherms to endotherms.

Daily body temperature rhythm (BTR) is essential for maintaining homeostasis. BTR is regulated separately from locomotor activity rhythms, but its molecular basis is largely unknown. While mammals internally regulate BTR, ectotherms, including Drosophila, exhibit temperature preference rhythm (TPR) behavior to regulate BTR. Here, we demonstrate that the diuretic hormone 31 receptor (DH31R) mediates TPR during the active phase in Drosophila. DH31R is expressed in clock cells, and its ligand, DH31, acts on clock cells to regulate TPR during the active phase. Surprisingly, the mouse homolog of DH31R, calcitonin receptor (Calcr), is expressed in the suprachiasmatic nucleus (SCN) and mediates body temperature fluctuations during the active phase in mice. Importantly, DH31R and Calcr are not required for coordinating locomotor activity rhythms. Our results represent the first molecular evidence that BTR is regulated distinctly from locomotor activity rhythms and show that DH31R/Calcr is an ancient specific mediator of BTR during the active phase in organisms ranging from ectotherms to endotherms.

Sleep and Skin Temperature in Preschool Children and Their Mothers

The purpose of this study was to investigate and compare sleep and skin temperature (Tsk) of preschool children with those of their mothers. The subjects included 18 pairs of preschool children and their mothers. The actigraphic measurement of sleep, Tsk, heart rate, bedroom climate, and the microclimate temperature and humidity (bed climate) were measured. Proximal and distal Tsk, the temperature gradient of distal and proximal Tsk (DPG), and bed climate temperature were significantly lower in the children. Approximately 70% of the children slept without bed covering. Heat dissipation during sleep in preschool children may primarily rely on the proximal Tsk. The lower Tsk than adults, and behavioral thermoregulation, may be important for sleep in preschoolers.

Breaking Up Sitting with Light-Intensity Physical Activity: Implications for Shift-Workers

Prolonged sitting, restricted sleep, and circadian disruption are all independent risk factors for non-communicable diseases. Previous research has demonstrated that breaking up sitting with light-intensity physical activity has clear benefits for the health of day workers, but these findings may not apply in the presence of sleep restriction and/or circadian disruption-both of which are commonly experienced by shift-workers. Specifically, sleep restriction, and circadian disruption result in acute physiological changes that may offset the benefits of breaking up sitting. This commentary will explore the potential benefits of breaking up sitting for health, work performance, and subsequent sleep in shift-workers. Future areas of research designed to understand the mechanisms by which prolonged sitting and shift work impact worker health and safety and to support the design of effective occupational health and safety interventions are proposed.

Drosophila DH31 Neuropeptide and PDF Receptor Regulate Night-Onset Temperature Preference

Body temperature exhibits rhythmic fluctuations over a 24 h period (Refinetti and Menaker, 1992) and decreases during the night, which is associated with sleep initiation (Gilbert et al., 2004; Kräuchi, 2007a,b). However, the underlying mechanism of this temperature decrease is largely unknown. We have previously shown that Drosophila exhibit a daily temperature preference rhythm (TPR), in which their preferred temperatures increase during the daytime and then decrease at the transition from day to night (night-onset) (Kaneko et al., 2012). Because Drosophila are small ectotherms, their body temperature is very close to that of the ambient temperature (Stevenson, 1985), suggesting that their TPR generates their body temperature rhythm. Here, we demonstrate that the neuropeptide diuretic hormone 31 (DH31) and pigment-dispersing factor receptor (PDFR) contribute to regulate the preferred temperature decrease at night-onset. We show that PDFR and tethered-DH31 expression in dorsal neurons 2 (DN2s) restore the preferred temperature decrease at night-onset, suggesting that DH31 acts on PDFR in DN2s. Notably, we previously showed that the molecular clock in DN2s is important for TPR. Although PDF (another ligand of PDFR) is a critical factor for locomotor activity rhythms, Pdf mutants exhibit normal preferred temperature decreases at night-onset. This suggests that DH31-PDFR signaling specifically regulates a preferred temperature decrease at night-onset. Thus, we propose that night-onset TPR and locomotor activity rhythms are differentially controlled not only by clock neurons but also by neuropeptide signaling in the brain.

SIGNIFICANCE STATEMENT

Body temperature rhythm (BTR) is fundamental for the maintenance of functions essential for homeostasis, such as generating metabolic energy and sleep. One major unsolved question is how body temperature decreases dramatically during the night. Previously, we demonstrated that a BTR-like mechanism, referred to as temperature preference rhythm (TPR), exists in Drosophila Here, we demonstrate that the diuretic hormone 31 (DH31) neuropeptide and pigment-dispersing factor receptor (PDFR) regulate preferred temperature decreases at night-onset via dorsal neurons 2. This is the first in vivo evidence that DH31 could function as a ligand of PDFR. Although both DH31 and PDF are ligands of PDFR, we show that DH31 regulates night-onset TPR, but PDF does not, suggesting that night-onset TPR and locomotor activity rhythms are controlled by different neuropeptides via different clock cells.

The role of PDF neurons in setting the preferred temperature before dawn in Drosophila

Animals have sophisticated homeostatic controls. While mammalian body temperature fluctuates throughout the day, small ectotherms, such as Drosophila achieve a body temperature rhythm (BTR) through their preference of environmental temperature. Here, we demonstrate that pigment dispersing factor (PDF) neurons play an important role in setting preferred temperature before dawn. We show that small lateral ventral neurons (sLNvs), a subset of PDF neurons, activate the dorsal neurons 2 (DN2s), the main circadian clock cells that regulate temperature preference rhythm (TPR). The number of temporal contacts between sLNvs and DN2s peak before dawn. Our data suggest that the thermosensory anterior cells (ACs) likely contact sLNvs via serotonin signaling. Together, the ACs-sLNs-DN2s neural circuit regulates the proper setting of temperature preference before dawn. Given that sLNvs are important for sleep and that BTR and sleep have a close temporal relationship, our data highlight a possible neuronal interaction between body temperature and sleep regulation.

DOI:http://dx.doi.org/10.7554/eLife.23206.001

Disciplined sleep for healthy living: Role of noradrenaline

Sleep is essential for maintaining normal physiological processes. It has been broadly divided into rapid eye movement sleep (REMS) and non-REMS (NREMS); one spends the least amount of time in REMS. Sleep (both NREMS and REMS) disturbance is associated with most altered states, disorders and pathological conditions. It is affected by factors within the body as well as the environment, which ultimately modulate lifestyle. Noradrenaline (NA) is one of the key molecules whose level increases upon sleep-loss, REMS-loss in particular and it induces several REMS-loss associated effects and symptoms. The locus coeruleus (LC)-NAergic neurons are primarily responsible for providing NA throughout the brain. As those neurons project to and receive inputs from across the brain, they are modulated by lifestyle changes, which include changes within the body as well as in the environment. We have reviewed the literature showing how various inputs from outside and within the body integrate at the LC neuronal level to modulate sleep (NREMS and REMS) and vice versa. We propose that these changes modulate NA levels in the brain, which in turn is responsible for acute as well as chronic psycho-somatic disorders and pathological conditions.