Impact of Sleep and Circadian Disruption on Energy Balance and Diabetes: A Summary of Workshop Discussions

Marine n-3 polyunsaturated fatty acids slow sleep impairment progression by regulating central circadian rhythms in type 2 diabetes

The role of marine n-3 polyunsaturated fatty acids (PUFAs) in promoting sleep has been proposed, yet their benefits for patients with type 2 diabetes (T2D) and the underlying molecular mechanisms remain poorly understood. In this study, we identify a significant association between habitual fish oil use and improved sleep quality in a cohort of 27,549 patients with T2D. A subsequent randomized controlled trial demonstrates that fish oil supplementation enhances sleep parameters in patients with T2D, accompanied by the upregulation of core circadian clock genes, including Clock, Bmal1, and Per2. In vitro, DHA and EPA restore the rhythmic oscillations of key clock genes in hypothalamic neurons disrupted by palmitic acid. Notably, n-3 PUFAs target RORα to regulate circadian clock oscillations and facilitate BMAL1 nuclear translocation. Collectively, our findings highlight the potential of marine n-3 PUFAs as a dietary intervention to improve sleep health in patients with T2D. This study was registered at ClinicalTrials.gov (NCT03708887).

Assessment of an App-Based Sleep Program to Improve Sleep Outcomes in a Clinical Insomnia Population: Randomized Controlled Trial

BACKGROUND

Insomnia is the most commonly reported sleep disturbance and significantly impacts mental health and quality of life. Traditional treatments for insomnia include pharmacological interventions or cognitive behavioral therapy for insomnia (CBT-I), but these options may not be accessible to everyone who needs treatment.

OBJECTIVE

This study aims to assess the effectiveness of the app-based Headspace Sleep Program in adults with clinical insomnia on sleep disturbance and mental health outcomes, compared with a waitlist control group.

METHODS

This randomized controlled trial included 132 adults with clinical insomnia who were assigned to either the Headspace Sleep Program (an 18-session self-guided, in-app program utilizing CBT-I techniques augmented by mindfulness) or a waitlist control group. Sleep disturbance outcomes were assessed by changes in insomnia symptoms (measured using the Insomnia Severity Index) and sleep efficiency (measured via sleep diary and actigraphy). Mental health outcomes included perceived stress (measured by the 10-item Perceived Stress Scale), depressive symptoms (measured by the 8-item Patient Health Questionnaire), sleep quality (measured by the Pittsburgh Sleep Quality Index), anxiety symptoms (measured by the 7-item Generalized Anxiety Disorder Scale), and mindfulness (measured by the Mindful Attention Awareness Scale). Changes from baseline to postintervention and follow-up were assessed for each outcome.

RESULTS

Participants had a mean (SD) age of 37.2 (10.6) years, with 69 out of 132 (52.3%) identifying as female. Those randomized to the Headspace Sleep Program group experienced significantly greater improvements in insomnia symptoms from baseline to postintervention and follow-up compared with participants in the waitlist control group (P<.001, η²p=0.107). Improvements from baseline to postintervention and follow-up were also observed in the Headspace Sleep Program group for sleep efficiency, as measured by both sleep diary (P=.01, η²p=.03) and actigraphy outcomes (P=.01, η²p=.03). Participants in the Headspace Sleep Program group showed greater improvements in insomnia remission rates (8/66, 12%, at postintervention and 9/66, 14%, at follow-up) and treatment response (11/66, 17%, at postintervention and 15/66, 23%, at follow-up) compared with the control group (remission rate 2/66, 3%, at postintervention and 0/66, 0%, at follow-up; treatment response 3/66, 5%, at postintervention and 1/66, 2%, at follow-up). The results suggest significant improvements in depressive symptoms (P=.01, η²p=.04), anxiety symptoms (P=.02, η²p=.02), and mindfulness (P=.01, η²p=.03) in the Headspace Sleep Program group.

CONCLUSIONS

The Headspace Sleep Program is an effective intervention for improving sleep disturbances in adults with clinical insomnia.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05872672; https://clinicaltrials.gov/ct2/show/NCT05872672.

Sleep rescues age-associated loss of glial engulfment

Neuronal injury due to trauma or neurodegeneration is a common feature of aging. The clearance of damaged neurons by glia is thought to be critical for maintenance of proper brain function. Sleep loss has been shown to inhibit the motility and function of glia that clear damaged axons while enhancement of sleep promotes clearance of damaged axons. Despite the potential role of glia in maintenance of brain function and protection against neurodegenerative disease, surprisingly little is known about how sleep loss impacts glial function in aged animals. Axotomy of the Drosophila antennae triggers Wallerian degeneration, where specialized olfactory ensheathing glia engulf damaged neurites. This glial response provides a robust model system to investigate the molecular basis for glial engulfment and neuron-glia communication. Glial engulfment is impaired in aged and sleep-deprived animals, raising the possibility that age-related sleep loss underlies deficits in glial function. To define the relationship between sleep- and age-dependent reductions in glial function, we restored sleep to aged animals and examined the effects on glial clearance of damaged axons. Both pharmacological and genetic induction of sleep restores clearance of damaged neurons in aged flies. Further analysis revealed that sleep restored post-injury induction of the engulfment protein Draper to aged flies, fortifying the notion that loss of sleep contributes to reduced glial-mediated debris clearance in aged animals. To identify age-related changes in the transcriptional response to neuronal injury, we used single-nucleus RNA-seq of the central brains from axotomized young and old flies. We identified broad transcriptional changes within the ensheathing glia of young flies, and the loss of transcriptional induction of autophagy-associated genes. We also identify age-dependent loss of transcriptional induction of 18 transcripts encoding for small and large ribosomal protein subunits following injury in old flies, suggesting dysregulation of ribosomal biogenesis contributes to loss of glial function. Together, these findings demonstrate a functional link between sleep loss, aging and Wallerian degeneration.

Association of outdoor artificial light at night on blood pressure and hypertension: Insights from a population-based survey

Artificial light at night (ALAN) is a growing environmental issue associated with negative health outcomes. Yet, there is a dearth of evidence concerning its effect on blood pressure (BP), especially in Ghana. This study examined the associations between ALAN, blood pressure, and hypertension. The study used data from 13,784 participants in the 2014 Ghana Demographic and Health Survey (GDHS). VIIRS Nighttime Day/Night Band dataset within the Google Earth was used to assess ALAN. Data on BP were obtained from the 2014 GDHS. Linear and logistic mixed effects models were used to analyze the data. Findings showed that higher ALAN score was associated with higher systolic blood pressure (SBP), diastolic blood pressure (DBP), and higher odds of hypertension. We observed higher percentages of SBP, DBP, and hypertension among the majority ethnic populations compared to the minority. Public health interventions should aim to reduce ALAN exposure to benefit human health.

Sex Differences in Circadian Timing and Biological Night in Adolescents

Circadian rhythms, intrinsic 24-h cycles that drive rhythmic changes in behavior and physiology, are important for normal physiology and health. Previous work in adults has identified sex differences in circadian rhythms of melatonin, temperature, and the intrinsic period of the human circadian timing system. However, less is known about sex differences in circadian rhythms at other developmental stages. To address this gap, we considered a secondary analysis of sleep and circadian data from two studies involving adolescent participants during the academic year: (n = 32, 15 females). We collected 1 week of in-home actigraphy data to calculate sleep-wake parameters and in-laboratory salivary melatonin data collection in dim-light conditions was used to compute dim-light melatonin onset (DLMO) and offset (DLMOff) using a threshold of 4 pg/mL. We found that DLMO was an average of 96 min earlier, the time between DLMO and bedtime was an average of 56 min greater, and the biological night (time between DLMO and DLMOff) was 60 min longer in females compared to males, even though bedtimes and waketimes were not statistically different between the groups. In addition, after accounting for differences in bedtime, sex was still a significant predictor of DLMO. Conversely, no evidence was found indicating a difference in DLMOff or the phase angle between DLMOff and waketime by sex. These findings suggest that sex differences in circadian rhythms are present in adolescents and may have implications for circadian health during this important developmental period.

The Circadian Brain and Cognition

Circadian rhythms are inherent to living organisms from single cells to humans and operate on a genetically determined cycle of approximately 24 hours. These endogenous rhythms are aligned with the external light/dark cycle of the Earth's rotation and offer the advantage of anticipating environmental changes. Circadian rhythms act directly on human cognition and indirectly through their fundamental influence on sleep/wake cycles. The strength of the circadian regulation of performance depends on the accumulated sleep debt and the cognitive domain, and it has been suggested to involve the activation of ascending arousal systems and their interaction with attention and other cognitive processes. In addition, attention-related cortical responses show extensive circadian rhythms, the phases of which vary across brain regions. This review discusses the impact of the circadian system on sleep/wake regulation and cognitive performance. It further addresses the health implications of circadian disruption, particularly in relation to mental and neurological disorders.

Nocturnal Light Pollution Synergistically Impairs Glucose Metabolism With Age and Weight in Monkeys

Over the past decades, the global prevalence of Type 2 diabetes mellitus (T2D) and impaired glucose tolerance (IGT) has been increasing at an epidemic rate, yet the exact cause remains unknown. It is widely accepted that glucose metabolism can be impaired by circadian rhythms and sleep disturbances. Concurrently, exposures to light at night have been closely linked to circadian and sleep disturbances. However, there is no direct experiment on primates to demonstrate the precise extent of how serious light pollution impairs glucose metabolism, whether people will eventually become accustomed to this environment, and whether the pollution has synergistic impairing effects with aging and weight on glucose metabolism. To quantitatively address these questions, 137 cynomolgus were exposed to three distinct nocturnal light intensities for consecutive 10 months. Monthly glucose metabolism assessments were conducted. Data pertaining to the mortality rate of preexisting diabetes, incidence of light-induced diabetes and IGT, and alterations in insulin secretion were collected and analyzed. The results show that nocturnal light (1) caused premature deaths in individuals with preexisting diabetes; (2) intensity-dependently induced diabetes and IGT in previous healthy monkeys; (3) intensity-dependently reduced melatonin secretion; (4) had a synergistic impairing effect on glucose metabolism with aging and weight; and (5) although monkeys would eventually adapt to the environment, the disrupted glucose metabolism would not fully recover in most individuals. In conclusion, nocturnal light is associated with the global high prevalence of T2D and IGT. The harmful effects of light pollution on glucose metabolism are synergistic with age and weight.

Postprandial Sleep in Short-Sleeping Mexican Cavefish

Interactions between sleep and feeding behaviors are critical for adaptive fitness. Diverse species suppress sleep when food is scarce to increase the time spent foraging. Postprandial sleep, an increase in sleep time following a feeding event, has been documented in vertebrate and invertebrate animals. While interactions between sleep and feeding appear to be highly conserved, the evolution of postprandial sleep in response to changes in food availability remains poorly understood. Multiple populations of the Mexican cavefish, Astyanax mexicanus, have independently evolved sleep loss and increased food consumption compared to surface-dwelling fish of the same species, providing the opportunity to investigate the evolution of interactions between sleep and feeding. Here, we investigate the effects of feeding on sleep in larval and adult surface fish, and in two parallelly evolved cave populations of A. mexicanus. Larval surface and cave populations of A. mexicanus increase sleep immediately following a meal, providing the first evidence of postprandial sleep in a fish model. The amount of sleep was not correlated to meal size and occurred independently of feeding time. In contrast to larvae, postprandial sleep was not detected in adult surface or cavefish, which can survive for months without food. Together, these findings reveal that postprandial sleep is present in multiple short-sleeping populations of cavefish, suggesting sleep-feeding interactions are retained despite the evolution of sleep loss. These findings raise the possibility that postprandial sleep is critical for energy conservation and survival in larvae that are highly sensitive to food deprivation.

Elevated DNA Damage without signs of aging in the short-sleeping Mexican Cavefish

Dysregulation of sleep has widespread health consequences and represents an enormous health burden. Short-sleeping individuals are predisposed to the effects of neurodegeneration, suggesting a critical role for sleep in the maintenance of neuronal health. While the effects of sleep on cellular function are not completely understood, growing evidence has identified an association between sleep loss and DNA damage, raising the possibility that sleep facilitates efficient DNA repair. The Mexican tetra fish, Astyanax mexicanus provides a model to investigate the evolutionary basis for changes in sleep and the consequences of sleep loss. Multiple cave-adapted populations of these fish have evolved to sleep for substantially less time compared to surface populations of the same species without identifiable impacts on healthspan or longevity. To investigate whether the evolved sleep loss is associated with DNA damage and cellular stress, we compared the DNA Damage Response (DDR) and oxidative stress levels between A. mexicanus populations. We measured markers of chronic sleep loss and discovered elevated levels of the DNA damage marker γH2AX in the brain, and increased oxidative stress in the gut of cavefish, consistent with chronic sleep deprivation. Notably, we found that acute UV-induced DNA damage elicited an increase in sleep in surface fish but not in cavefish. On a transcriptional level, only the surface fish activated the photoreactivation repair pathway following UV damage. These findings suggest a reduction of the DDR in cavefish compared to surface fish that coincides with elevated DNA damage in cavefish. To examine DDR pathways at a cellular level, we created an embryonic fibroblast cell line from the two populations of A. mexicanus. We observed that both the DDR and DNA repair were diminished in the cavefish cells, corroborating the in vivo findings and suggesting that the acute response to DNA damage is lost in cavefish. To investigate the long-term impact of these changes, we compared the transcriptome in the brain and gut of aged surface fish and cavefish. Strikingly, many genes that are differentially expressed between young and old surface fish do not transcriptionally vary by age in cavefish. Taken together, these findings suggest that cavefish have developed resilience to sleep loss, despite possessing cellular hallmarks of chronic sleep deprivation.

Targeted single cell expression profiling identifies integrators of sleep and metabolic state

Animals modulate sleep in accordance with their internal and external environments. Metabolic cues are particularly potent regulators of sleep, allowing animals to alter their sleep timing and amount depending on food availability and foraging duration. The fruit fly, Drosophila melanogaster, suppresses sleep in response to acute food deprivation, presumably to forage for food. This process is dependent on a single pair of Lateral Horn Leucokinin (LHLK) neurons, that secrete the neuropeptide Leucokinin. These neurons signal to insulin producing cells and suppress sleep under periods of starvation. The identification of individual neurons that modulate sleep-metabolism interactions provides the opportunity to examine the cellular changes associated with sleep modulation. Here, we use single-cell sequencing of LHLK neurons to examine the transcriptional responses to starvation. We validate that a Patch-seq approach selectively isolates RNA from individual LHLK neurons. Single-cell CEL-Seq comparisons of LHLK neurons between fed and 24-hr starved flies identified 24 genes that are differentially expressed in accordance with starvation state. In total, 12 upregulated genes and 12 downregulated genes were identified. Gene-ontology analysis showed an enrichment for Attacins, a family of anti-microbial peptides, along with several transcripts with diverse roles in regulating cellular function. Targeted knockdown of differentially expressed genes identified multiple genes that function within LHLK neurons to regulate sleep-metabolism interactions. Functionally validated genes include an essential role for the E3 ubiquitin Ligase insomniac, the sorbitol dehydrogenase Sodh1, as well as AttacinC and AttacinB in starvation-induced sleep suppression. Taken together, these findings provide a pipeline for identifying novel regulators of sleep-metabolism interactions within individual neurons.

Association of habitual sleep duration with abnormal bowel symptoms: a cross-sectional study of the 2005-2010 national health and nutrition examination survey

OBJECTIVES

Nowadays, few studies have examined the relationships between sleep duration and abnormal gut health. In this study, we used data from the National Health and Nutrition Examination Survey (NHANES) to investigate the correlations between habitual sleep duration and abnormal bowel symptoms in adults.

METHODS

This study included 11,533 participants aged ≥ 20 years from the NHANES conducted during 2005-2010. Chronic constipation and chronic diarrhea were defined based on the Bristol Stool Form Scale (BSFS) and frequency of bowel movements. Sleep duration was assessed based on the self-report questionnaire and classified into three groups: short sleep duration (< 7 h), normal sleep duration (7-9 h), and long sleep duration (> 9 h). Weighted data were calculated according to analytical guidelines. Logistic regression models and restricted cubic spline curves (RCS) were used to assess and describe the association between sleep duration and chronic diarrhea and constipation. Univariate and stratified analyses were also performed.

RESULTS

There were 949 (7.27%) adults aged 20 years and older with chronic diarrhea and 1120 (8.94%) adults with constipation among the 11,533 individuals. A positive association was found between short sleep duration and chronic constipation, with a multivariate-adjusted OR of 1.32 (95% CI: 1.05-1.66). Additionally, long sleep duration was significantly associated with an increased risk of chronic diarrhea (OR: 1.75, 95% CI: 1.08-2.84, P = 0.026). The RCS models revealed a statistically significant nonlinear association (P for non-linearity < 0.05) between sleep duration and chronic diarrhea. Furthermore, obesity was found to modify the association between sleep duration and chronic diarrhea and constipation (p for interaction = 0.044).

CONCLUSIONS

This study suggests that both long and short sleep durations are associated with a higher risk of chronic diarrhea and constipation in the general population. Furthermore, a non-linear association between sleep duration and these conditions persists even after adjusting for case complexities.

Postprandial sleep in short-sleeping Mexican cavefish

Interaction between sleep and feeding behaviors are critical for adaptive fitness. Diverse species suppress sleep when food is scarce to increase the time spent foraging. Post-prandial sleep, an increase in sleep time following a feeding event, has been documented in vertebrate and invertebrate animals. While interactions between sleep and feeding appear to be highly conserved, the evolution of postprandial sleep in response to changes in food availability remains poorly understood. Multiple populations of the Mexican cavefish, Astyanax mexicanus, have independently evolved sleep loss and increased food consumption compared to surface-dwelling fish of the same species, providing the opportunity to investigate the evolution of interactions between sleep and feeding. Here, we investigate effects of feeding on sleep in larval and adult surface fish, and two parallelly evolved cave populations of A. mexicanus. Larval surface and cave populations of A. mexicanus increase sleep immediately following a meal, providing the first evidence of postprandial sleep in a fish model. The amount of sleep was not correlated to meal size and occurred independently of feeding time. In contrast to larvae, postprandial sleep was not detected in adult surface or cavefish, that can survive for months without food. Together, these findings reveal that postprandial sleep is present in multiple short-sleeping populations of cavefish, suggesting sleep-feeding interactions are retained despite the evolution of sleep loss. These findings raise the possibility that postprandial sleep is critical for energy conservation and survival in larvae that are highly sensitive to food deprivation.

Pioneering new frontiers in circadian medicine chronotherapies for cardiovascular health

Cardiovascular disease (CVD) is a global health concern. Circadian medicine improves cardiovascular care by aligning treatments with our body's daily rhythms and their underlying cellular circadian mechanisms. Time-based therapies, or chronotherapies, show special promise in clinical cardiology. They optimize treatment schedules for better outcomes with fewer side effects by recognizing the profound influence of rhythmic body cycles. In this review, we focus on three chronotherapy areas (medication, light, and meal timing) with potential to enhance cardiovascular care. We also highlight pioneering research in the new field of rest, the gut microbiome, novel chronotherapies for hypertension, pain management, and small molecules that targeting the circadian mechanism.

Ontogeny and social context regulate the circadian activity patterns of Lake Malawi cichlids

Activity patterns tend to be highly stereotyped and critical for executing many different behaviors including foraging, social interactions, and predator avoidance. Differences in the circadian timing of locomotor activity and rest periods can facilitate habitat partitioning and the exploitation of novel niches. As a consequence, closely related species often display highly divergent activity patterns, suggesting that shifts from diurnal to nocturnal behavior, or vice versa, are critical for survival. In Africa's Lake Malawi alone, there are over 500 species of cichlids, which inhabit diverse environments and exhibit extensive phenotypic variation. We have previously identified a substantial range in activity patterns across adult Lake Malawi cichlid species, from strongly diurnal to strongly nocturnal. In many species, including fishes, ecological pressures differ dramatically across life-history stages, raising the possibility that activity patterns may change over ontogeny. To determine if rest-activity patterns change across life stages, we compared the locomotor patterns of six Lake Malawi cichlid species. While total rest and activity did not change between early juvenile and adult stages, rest-activity patterns did, with juveniles displaying distinct activity rhythms that are more robust than adults. One distinct difference between juveniles and adults is the emergence of complex social behavior. To determine whether social context is required for activity rhythms, we next measured locomotor behavior in group-housed adult fish. We found that when normal social interactions were allowed, locomotor activity patterns were restored, supporting the notion that social interactions promote circadian regulation of activity in adult fish. These findings reveal a previously unidentified link between developmental stage and social interactions in the circadian timing of cichlid activity.

Effects of sleep quality in early pregnancy on pregnancy outcomes and mood state

PURPOSE

To clarify the relationship between quality of sleep and pregnancy outcomes and to explore how sleep quality affects mood state in the first trimester of pregnancy.

METHODS

This prospective cohort study enrolled pregnant women from June 2020 to June 2021. Maternal sleep conditions, daytime sleepiness, and mood state in the first trimester were assessed using four Chinese self-rating scales, namely, the Pittsburgh Sleep Quality Index (PSQI), the Sleep Hygiene Practice Scale (SHPS), Epworth Sleepiness Scale (ESS), and the abbreviated version of the Profile of Mood States (a-POMS). Participants were divided into an exposed group (PSQI score > 5, poor sleep quality group) and a non-exposed group (PSQI score ≤ 5, good sleep quality group). Maternal characteristics, pregnancy outcomes, and the relationship among sleep quality, sleepiness, and mood state were analyzed. Comparisons of sleep hygiene behavior variables between the two subgroups were also analyzed.

RESULTS

A total of 2703 pregnant women were enrolled in the study. Poor sleep quality increased the probability of gestational diabetes mellitus (GDM) (1.573, 1.315-1.863), liver function damage (1.467, 1.021-2.107), preterm delivery (1.468, 1.077-2.002), mild sleepiness (1.612, 1.357-1.915), and excessive sleepiness (2.134, 1.686-2.701). Poor maternal sleep quality was significantly associated with the occurrence of preterm premature rupture of membranes (1.947, 1.168-3.243) and perinatal death (1.003, 1.000-1.006). Additionally, a significant positive correlation between the PSQI score and the total mood disturbance (TMD) score was revealed by Spearman's correlation analysis (r = 0.378, P < 0.01). Enter Regression analysis demonstrated that sleep quality (R2 = 0.390, P < 0.01) and sleepiness (R2 = 0.234, P < 0.01) exerted significant direct effects on mood state during pregnancy. Furthermore, Spearman's correlation analysis indicated a positive association between the PSQI score and the SHPS total score (r = 0.227, P < 0.01).

CONCLUSIONS

Poor sleep quality is significantly associated with elevated rates of maternal mood disturbances, obstetric complications, and adverse outcomes in infants. The findings suggest that it may be useful to provide comprehensive sleep assessment and education on sleep hygiene during the early stages of pregnancy.

Targeted metabolomics-based understanding of the sleep disturbances in drug-naïve patients with schizophrenia

BACKGROUND

Sleep disturbances are a common occurrence in patients with schizophrenia, yet the underlying pathogenesis remain poorly understood. Here, we performed a targeted metabolomics-based approach to explore the potential biological mechanisms contributing to sleep disturbances in schizophrenia.

METHODS

Plasma samples from 59 drug-naïve patients with schizophrenia and 36 healthy controls were subjected to liquid chromatography-mass spectrometry (LC-MS) targeted metabolomics analysis, allowing for the quantification and profiling of 271 metabolites. Sleep quality and clinical symptoms were assessed using the Pittsburgh Sleep Quality Index (PSQI) and the Positive and Negative Symptom Scale (PANSS), respectively. Partial correlation analysis and orthogonal partial least squares discriminant analysis (OPLS-DA) model were used to identify metabolites specifically associated with sleep disturbances in drug-naïve schizophrenia.

RESULTS

16 characteristic metabolites were observed significantly associated with sleep disturbances in drug-naïve patients with schizophrenia. Furthermore, the glycerophospholipid metabolism (Impact: 0.138, p<0.001), the butanoate metabolism (Impact: 0.032, p=0.008), and the sphingolipid metabolism (Impact: 0.270, p=0.104) were identified as metabolic pathways associated with sleep disturbances in drug-naïve patients with schizophrenia.

CONCLUSIONS

Our study identified 16 characteristic metabolites (mainly lipids) and 3 metabolic pathways related to sleep disturbances in drug-naïve schizophrenia. The detection of these distinct metabolites provide valuable insights into the underlying biological mechanisms associated with sleep disturbances in schizophrenia.

Deletion of the Clock Gene Bmal2 Leads to Alterations in Hypothalamic Clocks, Circadian Regulation of Feeding, and Energy Balance

BMAL2 (ARNTL2) is a paralog of BMAL1 that can form heterodimers with the other circadian factors CLOCK and NPAS2 to activate transcription of clock and clock-controlled genes. To assess a possible role of Bmal2 in the circadian regulation of metabolism, we investigated daily variations of energy metabolism, feeding behavior, and locomotor behavior, as well as ability to anticipate restricted food access in male mice knock-out for Bmal2 (B2KO). While their amount of food intake and locomotor activity were normal compared with wild-type mice, B2KO mice displayed increased adiposity (1.5-fold higher) and fasted hyperinsulinemia (fourfold higher) and tended to have lower energy expenditure at night. Impairment of the master clock in the suprachiasmatic nuclei was evidenced by the shorter free-running period (-14 min/cycle) of B2KO mice compared with wild-type controls and by a loss of daily rhythmicity in expression of intracellular metabolic regulators (e.g., Lipoprotein lipase and Uncoupling protein 2). The circadian window of eating was longer in B2KO mice. The circadian patterns of food intake and meal numbers were bimodal in control mice but not in B2KO mice. In response to restricted feeding, food-anticipatory activity was almost prevented in B2KO mice, suggesting altered food clock that controls anticipation of food availability. In the mediobasal hypothalamus of B2KO mice, expression of genes coding orexigenic neuropeptides (including Neuropeptide y and Agouti-Related Peptide) was downregulated, while Lipoprotein lipase expression lost its rhythmicity. Together, these data highlight that BMAL2 has major impacts on brain regulation of metabolic rhythms, sleep-wake cycle, and food anticipation.

Effect of Isocaloric, Time-Restricted Eating on Body Weight in Adults With Obesity : A Randomized Controlled Trial

BACKGROUND

Time-restricted eating (TRE) lowers body weight in many studies. Whether TRE induces weight loss independent of reductions in calorie intake, as seen in rodent studies, is unknown.

OBJECTIVE

To determine the effect of TRE versus a usual eating pattern (UEP) on body weight in the setting of stable caloric intake.

DESIGN

Randomized, isocaloric feeding study. (ClinicalTrials.gov: NCT03527368).

SETTING

Clinical research unit.

PARTICIPANTS

Adults with obesity and prediabetes or diet-controlled diabetes.

INTERVENTION

Participants were randomly assigned 1:1 to TRE (10-hour eating window, 80% of calories before 1 p.m.) or UEP (≤16-hour window, ≥50% of calories after 5 p.m.) for 12 weeks. Both groups had the same nutrient content and were isocaloric with total calories determined at baseline.

MEASUREMENTS

Primary outcome was change in body weight at 12 weeks. Secondary outcomes were fasting glucose, homeostatic model assessment for insulin resistance (HOMA-IR), glucose area under the curve by oral glucose tolerance test, and glycated albumin. We used linear mixed models to evaluate the effect of interventions on outcomes.

RESULTS

All 41 randomly assigned participants (mean age, 59 years; 93% women; 93% Black race; mean BMI, 36 kg/m2) completed the intervention. Baseline weight was 95.6 kg (95% CI, 89.6 to 101.6 kg) in the TRE group and 103.7 kg (CI, 95.3 to 112.0 kg) in the UEP group. At 12 weeks, weight decreased by 2.3 kg (CI, 1.0 to 3.5 kg) in the TRE group and by 2.6 kg (CI, 1.5 to 3.7 kg) in the UEP group (average difference TRE vs. UEP, 0.3 kg [CI, -1.2 to 1.9 kg]). Change in glycemic measures did not differ between groups.

LIMITATION

Small, single-site study; baseline differences in weight by group.

CONCLUSION

In the setting of isocaloric eating, TRE did not decrease weight or improve glucose homeostasis relative to a UEP, suggesting that any effects of TRE on weight in prior studies may be due to reductions in caloric intake.

PRIMARY FUNDING SOURCE

American Heart Association.

Melatonin in energy control: Circadian time-giver and homeostatic monitor

Melatonin is a neurohormone synthesized from dietary tryptophan in various organs, including the pineal gland and the retina. In the pineal gland, melatonin is produced at night under the control of the master clock located in the suprachiasmatic nuclei of the hypothalamus. Under physiological conditions, the pineal gland seems to constitute the unique source of circulating melatonin. Melatonin is involved in cellular metabolism in different ways. First, the circadian rhythm of melatonin helps the maintenance of proper internal timing, the disruption of which has deleterious effects on metabolic health. Second, melatonin modulates lipid metabolism, notably through diminished lipogenesis, and it has an antidiabetic effect, at least in several animal models. Third, pharmacological doses of melatonin have antioxidative, free radical-scavenging, and anti-inflammatory properties in various in vitro cellular models. As a result, melatonin can be considered both a circadian time-giver and a homeostatic monitor of cellular metabolism, via multiple mechanisms of action that are not all fully characterized. Aging, circadian disruption, and artificial light at night are conditions combining increased metabolic risks with diminished circulating levels of melatonin. Accordingly, melatonin supplementation could be of potential therapeutic value in the treatment or prevention of metabolic disorders. More clinical trials in controlled conditions are needed, notably taking greater account of circadian rhythmicity.

Interorgan rhythmicity as a feature of healthful metabolism

The finding that animals with circadian gene mutations exhibit diet-induced obesity and metabolic syndrome with hypoinsulinemia revealed a distinct role for the clock in the brain and peripheral tissues. Obesogenic diets disrupt rhythmic sleep/wake patterns, feeding behavior, and transcriptional networks, showing that metabolic signals reciprocally control the clock. Providing access to high-fat diet only during the sleep phase (light period) in mice accelerates weight gain, whereas isocaloric time-restricted feeding during the active period enhances energy expenditure due to circadian induction of adipose thermogenesis. This perspective focuses on advances and unanswered questions in understanding the interorgan circadian control of healthful metabolism.

Causal Relationship between Gut Microbiota and Aneurysm: A Mendelian Randomization Study

INTRODUCTION

Observational studies have suggested a possible relationship between gut microbiota (GM) and aneurysm development. However, the nature of this association remains unclear due to the inherent limitations of observational research, such as reverse causation and confounding factors. To address this knowledge deficit, this study aimed to investigate and establish a causal link between GM and aneurysm development.

METHODS

Summary statistics regarding GM and aneurysms were collected from relevant genome-wide association studies. Two samples were used in mendelian randomization (MR). The principal MR technique utilized was inverse-variance weighting, a technique renowned for producing reliable causal effect estimations. Additional MR methods, including weighted median (WM), MR-Egger, MR-PRESSO, and simple mode methods, were employed to ensure the robustness of the aforementioned association and investigate potential biases. Sensitivity analyses were performed to determine the consistency of the MR findings.

RESULTS

Varying associations were observed between specific microbial taxa and the different aneurysms analyzed. A negative correlation was observed between aortic aneurysm (AA) and Lentisphaerae, Lentisphaeria, and Victivallales. Conversely, the genus FamilyXIIIUCG001 exhibited an increased risk association. Regarding abdominal AA, Victivallaceae showed a reduced risk, and Bilophila and Catenibacterium were associated with an increased risk. For thoracic AA, negative and positive correlations were observed with Lentisphaerae and Turicibacter, respectively. Lastly, in the case of cerebral aneurysm (CA), Firmicutes and Haemophilus were associated with a decreased risk, and Lachnoclostridium demonstrated an increased risk of association.

CONCLUSION

Our research has established causal relationships between specific GM components and various aneurysms. The obtained knowledge may aid in the development of microbiome-based interventions and the identification of novel biomarkers for targeted prevention strategies.

Circadian epidemiology: Structuring circadian causes of disease and practical implications

That disruptions of the body's internal clockwork can lead to negative health consequences, including cancer, is a plausible hypothesis. Yet, despite strong mechanistic and animal support, the International Agency for Research on Cancer (IARC) experts considered epidemiological evidence as limited regarding the carcinogenicity of "shift-work involving circadian disruption" (2007) and "night shift work" (2019). We use directed acyclic graphs (DAGs) to outline a concept of circadian causes that discloses challenges when choosing appropriate exposure variables. On this basis, we propose to move beyond shift-work alone as a direct cause of disease. Instead, quantifying chronodisruption as individual doses can lead to interpretable circadian epidemiology. The hypothesis is that doses of chronodisruption cause disrupted circadian organisation by leading to desynchronization of circadian rhythms. Chronodisruption can be conceptualized as the split physiological nexus of internal and external times. Biological (or internal) night - an individual's intrinsically favoured sleep time window - could be the backbone of circadian epidemiology. In practice, individual doses that cause disrupted circadian organisation are derived from the intersection of time intervals of being awake and an individual's biological night. After numerous studies counted work shifts, chronobiology may now advance circadian epidemiology with more specific dose estimation - albeit with greater challenges in measurement (time-dependent individual data) and analysis (time-dependent confounding).

Sleep and circadian hygiene practices association with sleep quality among Brazilian adults

Objective

To investigate the association of sleep and circadian hygiene practices (sleep-promoting and sleep-disturbing behaviors) with sleep quality indicators.

Methods

Participants (n = 2050; 18-65 y) were part of virtual population-based research. Logistic regression models were fitted to assess differences in the OR (95% CI) of poor quality with sleep-promoting/disturbing practices (time-of-day of exercise, pre-bedtime routine, naps, electronic devices with illuminated screens, caffeine and alcohol consumption, and smoking). Linear regression analyses evaluated differences in sleep duration, latency, and awakenings associated with the same variables. Restricted cubic splines were used to study the shape of the association of screen time before bed with sleep duration, latency, and awakenings. Analyses were adjusted for age, sex, region, marital status, educational level, evening diet quality, and BMI.

Results

Evening use of electronic devices with illuminated screens showed a negative effect on all sleep parameters. Reporting dinner as the largest meal and evening caffeine consumption was associated with shorter sleep duration and longer sleep latency. Smokers had higher odds of longer latency. A protective effect of morning exercises was demonstrated on sleep quality, latency, and awakenings. Alcohol consumers presented lower odds of poor quality and lower frequency of awakenings. Pre-bedtime practices showed no or negative effect on sleep outcomes.

Conclusions

Recommendations to promote sleep quality and prevent sleep-related problems, with corresponding circadian health benefits, should include engaging in regular exercise, preferably in the morning, and avoiding naps, heavy meals close to bedtime, caffeine, smoking, and evening screen exposure.

Sex differences in frailty among older adults

By definition, aging is a natural, gradual and continuous process. On the other hand, frailty reflects the increase in vulnerability to stressors and shortens the time without disease (health span) while longevity refers to the length of life (lifespan). The average life expectancy has significantly increased during the last few decades. A longer lifespan has been accompanied by an increase in frailty and decreased independence in older adults, with major differences existing between men and women. For example, women tend to live longer than men but also experience higher rates of frailty and disability. Sex differences prevent optimization of lifestyle interventions and therapies to effectively prevent frailty. Sex differences in frailty and aging are rooted in a complex interplay between uncontrollable (genetic, epigenetic, physiological), and controllable factors (psychosocial and lifestyle factors). Thus, understanding the underlying causes of sex differences in frailty and aging is essential for developing personalized interventions to promote healthy aging and improve quality of life in older men and women. In this review, we have discussed the key contributors and knowledge gaps related to sex differences in aging and frailty.

Neurofibromin 1 mediates sleep depth in Drosophila

Neural regulation of sleep and metabolic homeostasis are critical in many aspects of human health. Despite extensive epidemiological evidence linking sleep dysregulation with obesity, diabetes, and metabolic syndrome, little is known about the neural and molecular basis for the integration of sleep and metabolic function. The RAS GTPase-activating gene Neurofibromin (Nf1) has been implicated in the regulation of sleep and metabolic rate, raising the possibility that it serves to integrate these processes, but the effects on sleep consolidation and physiology remain poorly understood. A key hallmark of sleep depth in mammals and flies is a reduction in metabolic rate during sleep. Here, we examine multiple measures of sleep quality to determine the effects of Nf1 on sleep-dependent changes in arousal threshold and metabolic rate. Flies lacking Nf1 fail to suppress metabolic rate during sleep, raising the possibility that loss of Nf1 prevents flies from integrating sleep and metabolic state. Sleep of Nf1 mutant flies is fragmented with a reduced arousal threshold in Nf1 mutants, suggesting Nf1 flies fail to enter deep sleep. The effects of Nf1 on sleep can be localized to a subset of neurons expressing the GABAA receptor Rdl. Sleep loss has been associated with changes in gut homeostasis in flies and mammals. Selective knockdown of Nf1 in Rdl-expressing neurons within the nervous system increases gut permeability and reactive oxygen species (ROS) in the gut, raising the possibility that loss of sleep quality contributes to gut dysregulation. Together, these findings suggest Nf1 acts in GABA-sensitive neurons to modulate sleep depth in Drosophila.

"Weight loss is my goal and being healthy is my goal… I can get over the hot flashes": a qualitative exploration of menopausal transition experiences and preferences for weight management among White women

OBJECTIVES

A qualitative research study design was used to (1) describe experiences of White women during the menopausal transition, and (2) identify barriers and facilitators for participating in a lifestyle program targeting weight management.

METHODS

Perimenopausal and postmenopausal White women who self-reported a desire to lose or maintain weight participated in focus groups. Women were queried about their past diet, exercise, and weight management practices; menopausal transition; and specific components and considerations for developing a lifestyle program for weight management. Thematic analysis was conducted on coded transcripts and four main themes emerged, each containing three to six subthemes.

RESULTS

Twenty-eight White women (age 54 ± 3 y, body mass index 31.4 ± 9.5 kg/m 2 ) were enrolled. Overall, women felt menopause was a major life event that coincided with weight gain and frustrating body changes. Women already engaged in many different types of exercises and diets to lose weight. Women also talked to healthcare professionals about menopause but were disappointed in the support they received. Women were interested in a lifestyle program that included menopause-specific education, which focused on results beyond weight, which was flexible to their busy lifestyle, and which provided opportunities to build camaraderie among other women experiencing menopause.

CONCLUSIONS

This cohort of White women were interested in receiving menopause information and improving their overall health as part of a lifestyle program targeting weight management during this transition. Building camaraderie with other women affected by menopause is important to women, as is creating a lifestyle program that is flexible with daily life.

Timing Matters: The Interplay between Early Mealtime, Circadian Rhythms, Gene Expression, Circadian Hormones, and Metabolism-A Narrative Review

Achieving synchronization between the central and peripheral body clocks is essential for ensuring optimal metabolic function. Meal timing is an emerging field of research that investigates the influence of eating patterns on our circadian rhythm, metabolism, and overall health. This narrative review examines the relationship between meal timing, circadian rhythm, clock genes, circadian hormones, and metabolic function. It analyzes the existing literature and experimental data to explore the connection between mealtime, circadian rhythms, and metabolic processes. The available evidence highlights the importance of aligning mealtime with the body's natural rhythms to promote metabolic health and prevent metabolic disorders. Specifically, studies show that consuming meals later in the day is associated with an elevated prevalence of metabolic disorders, while early time-restricted eating, such as having an early breakfast and an earlier dinner, improves levels of glucose in the blood and substrate oxidation. Circadian hormones, including cortisol and melatonin, interact with mealtimes and play vital roles in regulating metabolic processes. Cortisol, aligned with dawn in diurnal mammals, activates energy reserves, stimulates appetite, influences clock gene expression, and synchronizes peripheral clocks. Consuming meals during periods of elevated melatonin levels, specifically during the circadian night, has been correlated with potential implications for glucose tolerance. Understanding the mechanisms of central and peripheral clock synchronization, including genetics, interactions with chronotype, sleep duration, and hormonal changes, provides valuable insights for optimizing dietary strategies and timing. This knowledge contributes to improved overall health and well-being by aligning mealtime with the body's natural circadian rhythm.

Pediatric sleep: current knowledge, gaps, and opportunities for the future

This White Paper addresses the current gaps in knowledge, as well as opportunities for future studies in pediatric sleep. The Sleep Research Society's Pipeline Development Committee assembled a panel of experts tasked to provide information to those interested in learning more about the field of pediatric sleep, including trainees. We cover the scope of pediatric sleep, including epidemiological studies and the development of sleep and circadian rhythms in early childhood and adolescence. Additionally, we discuss current knowledge of insufficient sleep and circadian disruption, addressing the neuropsychological impact (affective functioning) and cardiometabolic consequences. A significant portion of this White Paper explores pediatric sleep disorders (including circadian rhythm disorders, insomnia, restless leg and periodic limb movement disorder, narcolepsy, and sleep apnea), as well as sleep and neurodevelopment disorders (e.g. autism and attention deficit hyperactivity disorder). Finally, we end with a discussion on sleep and public health policy. Although we have made strides in our knowledge of pediatric sleep, it is imperative that we address the gaps to the best of our knowledge and the pitfalls of our methodologies. For example, more work needs to be done to assess pediatric sleep using objective methodologies (i.e. actigraphy and polysomnography), to explore sleep disparities, to improve accessibility to evidence-based treatments, and to identify potential risks and protective markers of disorders in children. Expanding trainee exposure to pediatric sleep and elucidating future directions for study will significantly improve the future of the field.

The role of insufficient sleep and circadian misalignment in obesity

Traditional risk factors for obesity and the metabolic syndrome, such as excess energy intake and lack of physical activity, cannot fully explain the high prevalence of these conditions. Insufficient sleep and circadian misalignment predispose individuals to poor metabolic health and promote weight gain and have received increased research attention in the past 10 years. Insufficient sleep is defined as sleeping less than recommended for health benefits, whereas circadian misalignment is defined as wakefulness and food intake occurring when the internal circadian system is promoting sleep. This Review discusses the impact of insufficient sleep and circadian misalignment in humans on appetite hormones (focusing on ghrelin, leptin and peptide-YY), energy expenditure, food intake and choice, and risk of obesity. Some potential strategies to reduce the adverse effects of sleep disruption on metabolic health are provided and future research priorities are highlighted. Millions of individuals worldwide do not obtain sufficient sleep for healthy metabolic functions. Furthermore, modern working patterns, lifestyles and technologies are often not conducive to adequate sleep at times when the internal physiological clock is promoting it (for example, late-night screen time, shift work and nocturnal social activities). Efforts are needed to highlight the importance of optimal sleep and circadian health in the maintenance of metabolic health and body weight regulation.

Variant-to-gene mapping followed by cross-species genetic screening identifies GPI-anchor biosynthesis as a regulator of sleep

Genome-wide association studies (GWAS) in humans have identified loci robustly associated with several heritable diseases or traits, yet little is known about the functional roles of the underlying causal variants in regulating sleep duration or quality. We applied an ATAC-seq/promoter focused Capture C strategy in human iPSC-derived neural progenitors to carry out a "variant-to-gene" mapping campaign that identified 88 candidate sleep effector genes connected to relevant GWAS signals. To functionally validate the role of the implicated effector genes in sleep regulation, we performed a neuron-specific RNA interference screen in the fruit fly, Drosophila melanogaster, followed by validation in zebrafish. This approach identified a number of genes that regulate sleep including a critical role for glycosylphosphatidylinositol (GPI)-anchor biosynthesis. These results provide the first physical variant-to-gene mapping of human sleep genes followed by a model organism-based prioritization, revealing a conserved role for GPI-anchor biosynthesis in sleep regulation.

Do lifestyle factors and quality of life differ in people with metabolically healthy and unhealthy obesity?

BACKGROUND AND OBJECTIVES

Although obesity is typically associated with metabolic co-morbidities, some people with obesity do not develop metabolic abnormalities. We evaluated whether modifiable lifestyle factors (i.e., physical activity, dietary composition, and sleep characteristics) can help explain why some people with obesity are metabolically healthy (MHO) and whether metabolically unhealthy obesity (MUO) affects quality of life (QOL).

SUBJECTS/METHODS

Physical activity and sleep characteristics were assessed by using tri-axial accelerometers and dietary intake, sleep quality, and QOL were evaluated by using validated questionnaires in people stratified into three groups: (1) lean with normal glucose tolerance, plasma triglyceride (TG) concentration and intrahepatic TG (IHTG) content (metabolically healthy lean [MHL]; n = 20); (2) obesity and normal glucose tolerance, plasma TG concentration and IHTG content (MHO; n = 36); and (3) obesity with abnormal glucose metabolism and hepatic steatosis (MUO; n = 43).

RESULTS

People with MHO performed ~45-min more light-intensity physical activity/day than the MHL and MUO groups (P < 0.05). QOL, particularly the physical function domain, was higher in the MHO than the MUO group (P < 0.05). Although self-reported intake of starch, dairy, and cured meats were higher in the MUO than the MHO group (P < 0.02), the absolute differences were small and unlikely to have metabolic effects. No differences were found in sleep duration or quality between groups.

CONCLUSIONS

These data suggest physical activity, but not sleep or dietary intake, contribute to better metabolic health in people with MHO than those with MUO, and that QOL is lower in people with MUO than those with MHO.

Multi-Timescale Rhythmicity of Blood Glucose and Insulin Delivery Reveals Key Advantages of Hybrid Closed Loop Therapy

BACKGROUND

Blood glucose and insulin exhibit coordinated daily and hourly rhythms in people without diabetes (nonT1D). Although the presence and stability of these rhythms are associated with euglycemia, it is unknown if they (1) are preserved in individuals with type 1 diabetes (T1D) and (2) vary by therapy type. In particular, Hybrid Closed Loop (HCL) systems improve glycemia in T1D compared to Sensor Augmented Pump (SAP) therapies, but the extent to which either recapitulates coupled glucose and insulin rhythmicity is not well described. In HCL systems, more rapid modulation of glucose via automated insulin delivery may result in greater rhythmic coordination and euglycemia. Such precision may not be possible in SAP systems. We hypothesized that HCL users would exhibit fewer hyperglycemic event, superior rhythmicity, and coordination relative to SAP users.

METHODS

Wavelet and coherence analyses were used to compare glucose and insulin delivery rate (IDR) within-day and daily rhythms, and their coordination, in 3 datasets: HCL (n = 150), SAP (n = 89), and nonT1D glucose (n = 16).

RESULTS

Glycemia, correlation between normalized glucose and IDR, daily coherence of glucose and IDR, and amplitude of glucose oscillations differed significantly between SAP and HCL users. Daily glucose rhythms differed significantly between SAP, but not HCL, users and nonT1D individuals.

CONCLUSIONS

SAP use is associated with greater hyperglycemia, higher amplitude glucose fluctuations, and a less stably coordinated rhythmic phenotype compared to HCL use. Improvements in glucose and IDR rhythmicity may contribute to the overall effectiveness of HCL systems.

Electronic Health Record-Based Recruitment and Retention and Mobile Health App Usage: Multisite Cohort Study

BACKGROUND

To address the obesity epidemic, there is a need for novel paradigms, including those that address the timing of eating and sleep in relation to circadian rhythms. Electronic health records (EHRs) are an efficient way to identify potentially eligible participants for health research studies. Mobile health (mHealth) apps offer available and convenient data collection of health behaviors, such as timing of eating and sleep.

OBJECTIVE

The aim of this descriptive analysis was to report on recruitment, retention, and app use from a 6-month cohort study using a mobile app called Daily24.

METHODS

Using an EHR query, adult patients from three health care systems in the PaTH clinical research network were identified as potentially eligible, invited electronically to participate, and instructed to download and use the Daily24 mobile app, which focuses on eating and sleep timing. Online surveys were completed at baseline and 4 months. We described app use and identified predictors of app use, defined as 1 or more days of use, versus nonuse and usage categories (ie, immediate, consistent, and sustained) using multivariate regression analyses.

RESULTS

Of 70,661 patients who were sent research invitations, 1021 (1.44%) completed electronic consent forms and online baseline surveys; 4 withdrew, leaving a total of 1017 participants in the analytic sample. A total of 53.79% (n=547) of the participants were app users and, of those, 75.3% (n=412), 50.1% (n=274), and 25.4% (n=139) were immediate, consistent, and sustained users, respectively. Median app use was 28 (IQR 7-75) days over 6 months. Younger age, White race, higher educational level, higher income, having no children younger than 18 years, and having used 1 to 5 health apps significantly predicted app use (vs nonuse) in adjusted models. Older age and lower BMI predicted early, consistent, and sustained use. About half (532/1017, 52.31%) of the participants completed the 4-month online surveys. A total of 33.5% (183/547), 29.3% (157/536), and 27.1% (143/527) of app users were still using the app for at least 2 days per month during months 4, 5, and 6 of the study, respectively.

CONCLUSIONS

EHR recruitment offers an efficient (ie, high reach, low touch, and minimal participant burden) approach to recruiting participants from health care settings into mHealth research. Efforts to recruit and retain less engaged subgroups are needed to collect more generalizable data. Additionally, future app iterations should include more evidence-based features to increase participant use.

Bone Turnover Markers After Six Nights of Insufficient Sleep and Subsequent Recovery Sleep in Healthy Men

PURPOSE

The goal of this study was to determine the bone turnover marker (BTM) response to insufficient and subsequent recovery sleep, independent of changes in posture, body weight, and physical activity.

METHODS

Healthy men (N = 12) who habitually slept 7-9 h/night were admitted to an inpatient sleep laboratory for a baseline 8 h/night sleep opportunity followed by six nights of insufficient sleep (5 h/night). Diet, physical activity, and posture were controlled. Serum markers of bone formation (osteocalcin, PINP) and resorption (β-CTX) were obtained over 24 h at baseline and on the last night of sleep restriction, and on fasted samples obtained daily while inpatient and five times after discharge over 3 weeks. Maximum likelihood estimates in a repeated measures model were used to assess the effect of insufficient and subsequent recovery sleep on BTM levels.

RESULTS

There was no statistically or clinically significant change in PINP (p = 0.53), osteocalcin (p = 0.66), or β-CTX (p = 0.10) in response to six nights of insufficient sleep. There were no significant changes in BTMs from the inpatient stay through 3 weeks of recovery sleep (all p [Formula: see text] 0.63). On average, body weight was stable during the inpatient stay (Δweight = - 0.55 ± 0.91 kg, p = 0.06).

CONCLUSION

No significant changes in serum BTMs were observed after six nights of insufficient or subsequent recovery sleep in young healthy men. Changes in weight and physical activity may be required to observe significant BTM change in response to sleep and circadian disruptions. Clinical Trials Registration Registered at ClinicalTrials.gov (NCT03733483) on November 7, 2018.

Sleep Disruption and Bone Health

PURPOSE OF REVIEW

Review recent literature investigating the relationship between bone health and sleep/circadian disruptions (e.g., abnormal sleep duration, night shift work).

RECENT FINDINGS

Short and long sleep are associated with low bone mineral density (BMD). Recent data from observational studies identified an increased risk of fracture in women with short sleep. Studies suggest that age, sex, weight change, and concurrent circadian misalignment may modify the effects of sleep restriction on bone metabolism. Interventional studies demonstrate alterations in bone metabolism and structure in response to circadian disruption that could underlie the increased fracture risk seen with night shift work. The effects of sleep and circadian disruption during adolescence may have lifelong skeletal consequences if they adversely impact bone modeling. Data suggest that short sleep and night shift work negatively impact bone metabolism and health. Rigorous studies of prevalent sleep and circadian disruptions are needed to determine mechanisms and develop prevention strategies to optimize lifelong skeletal health.

Effect of obstructive sleep apnea on glucose metabolism

BACKGROUND

Obstructive sleep apnea (OSA) is prevalent in people with obesity and is a major risk factor for type 2 diabetes (T2D). The effect of OSA on metabolic function and the precise mechanisms (insulin resistance, β-cell dysfunction, or both) responsible for the increased T2D risk in people with OSA are unknown.

DESIGN AND METHODS

We used a two-stage hyperinsulinemic-euglycemic clamp procedure in conjunction with stable isotopically labeled glucose and palmitate tracer infusions and 18F-fluorodeoxyglucose injection and positron emission tomography to quantify multi-organ insulin action and oral and intravenous tolerance tests to evaluate glucose-stimulated insulin secretion in fifteen people with obesity and OSA and thirteen people with obesity without OSA.

RESULTS

OSA was associated with marked insulin resistance of adipose tissue triglyceride lipolysis and glucose uptake into both skeletal muscles and adipose tissue, whereas there was no significant difference between the OSA and control groups in insulin action on endogenous glucose production, basal insulin secretion, and glucose-stimulated insulin secretion during both intravenous and oral glucose tolerance tests.

CONCLUSIONS

These data demonstrate that OSA is a key determinant of insulin sensitivity in people with obesity and underscore the importance of taking OSA status into account when evaluating metabolic function in people with obesity. These findings may also have important clinical implications because disease progression and the risk of diabetes-related complications vary by T2D subtype (i.e. severe insulin resistance vs insulin deficiency). People with OSA may benefit most from the targeted treatment of peripheral insulin resistance and early screening for complications associated with peripheral insulin resistance.

Suprachiasmatic nucleus-mediated glucose entry into the arcuate nucleus determines the daily rhythm in blood glycemia

Glycemia is maintained within very narrow boundaries with less than 5% variation at a given time of the day. However, over the circadian cycle, glycemia changes with almost 50% difference. How the suprachiasmatic nucleus, the biological clock, maintains these day-night variations with such tiny disparities remains obscure. We show that via vasopressin release at the beginning of the sleep phase, the suprachiasmatic nucleus increases the glucose transporter GLUT1 in tanycytes. Hereby GLUT1 promotes glucose entrance into the arcuate nucleus, thereby lowering peripheral glycemia. Conversely, blocking vasopressin activity or the GLUT1 transporter at the daily trough of glycemia increases circulating glucose levels usually seen at the peak of the rhythm. Thus, biological clock-controlled mechanisms promoting glucose entry into the arcuate nucleus explain why peripheral blood glucose is low before sleep onset.

Circadian Rhythm and Nuclear Receptors

All life of Earth has evolved mechanisms to track time. This permits anticipation of predictable changes in light/dark, and in most cases also directs fed/fasted cycles, and sleep/wake. The nuclear receptors enjoy a close relationship with the molecular machinery of the clock. Some play a core role within the circadian machinery, other respond to ligands which oscillate in concentration, and physical cross-talk between clock transcription factors, eg cryptochromes, and multiple nuclear receptors also enable coupling of nuclear receptor function to time of day. Essential processes including inflammation, and energy metabolism are strongly regulated by both the circadian machinery, and rhythmic behaviour, and also by multiple members of the nuclear receptor family. An emerging theme is reciprocal regulation of key processes by different members of the nuclear receptor family, for example NR1D1/2, and NR1F1, in regulation of the core circadian clock transcription factor BMAL1.

Body composition and cardiometabolic health across the menopause transition

Every year, 2 million women reach menopause in the United States, and they may spend 40% or more of their life in a postmenopausal state. In the years immediately preceding menopause-known as the menopause transition (or perimenopause)-changes in hormones and body composition increase a woman's overall cardiometabolic risk. In this narrative review, we summarize the changes in weight, body composition, and body fat distribution, as well as the changes in energy intake, energy expenditure, and other cardiometabolic risk factors (lipid profile, glucose metabolism, sleep health, and vascular function), that occur during the menopause transition. We also discuss the benefits of lifestyle interventions in women in the earlier stages of menopause before these detrimental changes occur. Finally, we discuss how to include perimenopausal women in research studies so that women across the life-span are adequately represented.

Time-restricted feeding prevents deleterious metabolic effects of circadian disruption through epigenetic control of β cell function

Circadian rhythm disruption (CD) is associated with impaired glucose homeostasis and type 2 diabetes mellitus (T2DM). While the link between CD and T2DM remains unclear, there is accumulating evidence that disruption of fasting/feeding cycles mediates metabolic dysfunction. Here, we used an approach encompassing analysis of behavioral, physiological, transcriptomic, and epigenomic effects of CD and consequences of restoring fasting/feeding cycles through time-restricted feeding (tRF) in mice. Results show that CD perturbs glucose homeostasis through disruption of pancreatic β cell function and loss of circadian transcriptional and epigenetic identity. In contrast, restoration of fasting/feeding cycle prevented CD-mediated dysfunction by reestablishing circadian regulation of glucose tolerance, β cell function, transcriptional profile, and reestablishment of proline and acidic amino acid–rich basic leucine zipper (PAR bZIP) transcription factor DBP expression/activity. This study provides mechanistic insights into circadian regulation of β cell function and corresponding beneficial effects of tRF in prevention of T2DM.

Influence of shift work on rest-activity rhythms, sleep quality, and fatigue of female nurses

Female nurses working rotating shifts must change their daily routines often, which affects their biological circadian rhythms and could cause sleep disorders and fatigue. The objective of this study was to compare the sleep-wake rhythms, sleep quality, and fatigue of female nurses working rotating shifts and fixed day shifts and to analyze the factors that influence their fatigue. Participants comprised a shift worker group of 101 nurses and a day worker group of 76 nurses. Following the collection of basic information of the nurses and their scores in the various constructs of the Pittsburg Sleep Quality Index (PSQI) and the Checklist Individual Strength (CIS) questionnaire, each nurse wore an actigraph for seven consecutive days to collect for analysis the sleep-wake rhythm parameter dichotomy index (I < O) and durations of continuous sleep and wake. Multivariable linear regression was then used to determine whether the influence of various variables on fatigue differed between the two groups. Results revealed that the sleep-wake rhythm parameter I < O of the day worker group was significantly higher than that of the shift worker group (t = 5.08, p < .001). The shift worker group exhibited significantly higher PSQI global scores (t = -2.00, p = .047), longer total sleep time (t = 2.07, p = .040), poorer habitual sleep efficiency (t = -3.06, p = .003), and greater use of sleeping medication (t = -2.90, p = .004) than did the day worker group. Multivariable linear regression was performed to analyze the important predictors of the CIS score in the two groups with body mass index, age, work experience, marital status, educational background, department of employment, shift type at the time of recruitment, sleep-wake rhythm parameter I < O, and quality of sleep as independent variables. Results indicated that in the shift worker group, the overall explanatory power (R²) of the multivariable linear regression model was 22.9% (F = 3.01, p = .003), and only the PSQI global score (β = 0.33, p = .003) influenced the CIS score. In the day worker group, the various variables did not influence the CIS score in the multivariable linear regression model. Although the female nurses working rotating shifts spent more time in bed, their sleep-wake rhythms and sleep quality were poorer than those of the day worker group. Furthermore, the sleep quality of female nurses in the shift worker group had a significant impact on their fatigue. In other words, for female nurses who must work rotating shifts, sleep quality determines whether fatigue can be reduced. The shift-working nurses themselves should implement sleep management, such as avoiding disruptions to their sleep-wake rhythm and improving sleep quality, which should be effective strategies to reduce fatigue.

Non-REM and REM/paradoxical sleep dynamics across phylogeny

All animals carefully studied sleep, suggesting that sleep as a behavioral state exists in all animal life. Such evolutionary maintenance of an otherwise vulnerable period of environmental detachment suggests that sleep must be integral in fundamental biological needs. Despite over a century of research, the knowledge of what sleep does at the tissue, cellular or molecular levels remain cursory. Currently, sleep is defined based on behavioral criteria and physiological measures rather than at the cellular or molecular level. Physiologically, sleep has been described as two main states, non-rapid eye moment (NREM) and REM/paradoxical sleep (PS), which are defined in the neocortex by synchronous oscillations and paradoxical wake-like activity, respectively. For decades, these two sleep states were believed to be defining characteristics of only mammalian and avian sleep. Recent work has revealed slow oscillation, silencing, and paradoxical/REM-like activities in reptiles, fish, flies, worms, and cephalopods suggesting that these sleep dynamics and associated physiological states may have emerged early in animal evolution. Here, we discuss these recent developments supporting the conservation of neural dynamics (silencing, oscillation, paradoxical activity) of sleep states across phylogeny.

Tianwang Buxin Granules Influence the Intestinal Flora in Perimenopausal Insomnia

Methods

The subjects included 13 PI patients from the Hubei Provincial Hospital of TCM, Hubei University of TCM, and Wuhan Traditional Chinese Medicine Hospital, and the corresponding noninsomniac spouses of the patients were selected as controls. TWBXG was continuously administered for 4 weeks. The feces of PI patients and their noninsomniac spouses before and after treatment with TWBXG were collected. The intestinal flora composition of each group was detected by metagenomic sequencing, and the efficacy of TWBXG was evaluated by the PSQI scale.

Results

Compared with the control group, the model group showed an increase in the abundance of Roseburia faecis, Ruminococcus, Prevotella copri, Fusicatenibacter saccharivorans, and Blautia obeum, while those of Bacteroides, fecal Bacteroidetes, and Faecalibacterium prausnitzii were decreased. Compared with pretreatment, the PSQI score was significantly reduced (P < 0.05), the abundance of Bacteroides, fecal Bacteroidetes, and Faecalibacterium prausnitzii increased, and that of Roseburia faecis, Ruminococcus, Prevotella copri, Fusicatenibacter saccharivorans, and Blautia obeum decreased after treatment. However, there was still a certain gap in the abundance of related flora in the treatment group compared with the control.

Conclusion

PI is associated with disturbances in the intestinal flora and is mainly related to the disorders of Roseburia faecis, Ruminococcus, Prevotella copri, Fusicatenibacter saccharivorans, Blautia obeum, Bacteroides, fecal Bacteroidetes, and Faecalibacterium prausnitzii. TWBXG can effectively treat PI, and its effect may be achieved by regulating the disordered intestinal flora. Clinical Trials. The study was registered in the Chinese clinical trial registry and approved by the World Health Organization clinical trial registration platform (Effects of the modified Tianwang Buxin granule and modified Tianwang Buxin decoction pieces on insomnia: a randomized, controlled trial, ChiCTR-IPR-17011549).

Social Jetlag and Cardiometabolic Risk in Preadolescent Children

Objective: Childhood cardiometabolic disease risk (CMD) has been associated with short sleep duration. Its relationship with other aspects of sleep should also be considered, including social jetlag (SJL) which represents the difference between a person's social rhythms and circadian clock. This study investigated whether childhood CMD risk is associated with sleep duration, sleep disturbances, and SJL.

Study Design: The observational study included 332 children aged 8–10 years (48.5% female). The three independent variables were sleep duration, sleep disturbances, and SJL. SJL was calculated as the variation in hours between the midpoint of sleep during free (weekend) days and work/school days. Eleven cardiometabolic biomarkers were measured, including central blood pressure, lipids, glycated hemoglobin, arterial wave reflection, and glucose. Underlying CMD risk factors were identified using factor analysis.

Results: Four underlying CMD risk factors were identified using factor analysis: blood pressure, cholesterol, vascular health, and carbohydrate metabolism. Neither sleep disturbances nor sleep duration were significantly associated with any of the four CMD factors following adjustments to potential confounders. However, SJL was significantly linked to vascular health (p = 0.027) and cholesterol (p = 0.025).

Conclusion: These findings suggest that SJL may be a significant and measurable public health target for offsetting negative CMD trajectories in children. Further studies are required to determine biological plausibility.

Circadian rhythms affect bone reconstruction by regulating bone energy metabolism

Metabolism is one of the most complex cellular biochemical reactions, providing energy and substances for basic activities such as cell growth and proliferation. Early studies have shown that glucose is an important nutrient in osteoblasts. In addition, amino acid metabolism and fat metabolism also play important roles in bone reconstruction. Mammalian circadian clocks regulate the circadian cycles of various physiological functions. In vertebrates, circadian rhythms are mediated by a set of central clock genes: muscle and brain ARNT like-1 (Bmal1), muscle and brain ARNT like-2 (Bmal2), circadian rhythmic motion output cycle stagnates (Clock), cryptochrome 1 (Cry1), cryptochrome2 (Cry2), period 1 (Per1), period 2 (Per2), period 3 (Per3) and neuronal PAS domain protein 2 (Npas2). Negative feedback loops, controlled at both the transcriptional and posttranslational levels, adjust these clock genes in a diurnal manner. According to the results of studies on circadian transcriptomic studies in several tissues, most rhythmic genes are expressed in a tissue-specific manner and are affected by tissue-specific circadian rhythms. The circadian rhythm regulates several activities, including energy metabolism, feeding time, sleeping, and endocrine and immune functions. It has been reported that the circadian rhythms of mammals are closely related to bone metabolism. In this review, we discuss the regulation of the circadian rhythm/circadian clock gene in osteoblasts/osteoclasts and the energy metabolism of bone, and the relationship between circadian rhythm, bone remodeling, and energy metabolism. We also discuss the therapeutic potential of regulating circadian rhythms or changing energy metabolism on bone development/bone regeneration.

Access to Daylight at Home Improves Circadian Alignment, Sleep, and Mental Health in Healthy Adults: A Crossover Study

As the primary environmental cue for the body’s master biological clock, light–dark patterns are key for circadian alignment and are ultimately fundamental to multiple dimensions of health including sleep and mental health. Although daylight provides the proper qualities of light for promoting circadian alignment, our modern indoor lifestyles offer fewer opportunities for adequate daylight exposure. This field study explores how increasing circadian-effective light in residences affects circadian phase, sleep, vitality, and mental health. In this crossover study, 20 residents spent one week in their apartments with electrochromic glass windows and another week with functionally standard windows with blinds. Calibrated light sensors revealed higher daytime circadian-effective light levels with the electrochromic glass windows, and participants exhibited consistent melatonin onset, a 22-min earlier sleep onset, and higher sleep regularity. In the blinds condition, participants exhibited a 15-min delay in dim light melatonin onset, a delay in subjective vitality throughout the day, and an overall lower positive affect. This study demonstrates the impact of daytime lighting on the physiological, behavioral, and subjective measures of circadian health in a real-world environment and stresses the importance of designing buildings that optimize daylight for human health and wellbeing.