Obesity and short sleep: unlikely bedfellows?

Associations of actigraph sleep characteristics with blood pressure among older adults

OBJECTIVES

Many studies have examined links between sleep and blood pressure, with mixed findings, mostly using self-reported sleep data and cross-sectional designs. We examined whether actigraph-estimated sleep characteristics are associated with concurrent blood pressure or 5-year blood pressure change in a national cohort of older adults (National Social Life, Health and Aging Project), and whether these associations differ by hypertension medication use.

METHODS

Subjects were 669 older adults (62-90years), 471 with 5-year follow-up data. Sleep characteristics were duration (linear plus quadratic terms); sleep percentage; and categorical onset, midpoint, and waking times. Multivariable linear models adjusted for age, race, gender, obesity, smoking, daytime napping, and hypertension medication use. Interactions between sleep characteristics and hypertension medication were tested among the 401 subjects with consistent hypertension medication status over time.

RESULTS

We found U-shaped cross-sectional and longitudinal relationships between duration and blood pressure, with shorter and longer sleep times associated with higher blood pressure. Later onset times were cross-sectionally associated with higher systolic blood pressure, while earlier onset times were longitudinally associated with systolic blood pressure increase. Midpoint, wake time, and sleep percentage were not significantly associated with blood pressure. Significant interaction terms suggested hypertension medications attenuated associations of sleep onset and wake time with diastolic blood pressure.

CONCLUSIONS

These results with actigraph-estimated parameters confirm some, but not all, associations reported from research based on self-reported sleep data. Our findings are consistent with recommended intermediate sleep durations for cardiovascular health and suggest hypertension medication may attenuate some associations between sleep timing and blood pressure.

Association of short sleep with risk of periodontal disease: A meta-analysis and Mendelian randomization study

AIM

The aim of this meta-analysis and Mendelian randomization (MR) study was to assess the association between short sleep and periodontal disease, including tooth loss and periodontitis.

MATERIALS AND METHODS

The meta-analysis of relevant studies was conducted to assess the association between short sleep and periodontal disease. MR analyses were conducted with the inverse-variance-weighted (IVW) method, weighted median method, MR-Egger method, and MR-Robust Adjusted Profile Score (RAPS) method to assess the causal effect of short sleep on tooth loss and periodontitis.

RESULTS

Seven cross-sectional studies involving 40,196 individuals were included in the meta-analysis. The association between short sleep and periodontal disease was not statistically significant (odds ratios (OR) =1.13, 95% confidence interval (CI): 0.99, 1.28; p = 0.076). In the MR analysis, we did not observe statistically significant causal associations of genetically determined short sleep with tooth loss (β: -0.056; 95% CI: -0.181 to 0.068; p = 0.376) and periodontitis (β: -0.112; 95% CI: -0.340 to 0.117; p = 0.339).

CONCLUSIONS

Short sleep is not associated with the risk of periodontal disease according to current evidence. Future studies need to pay attention to the measurement of sleep duration, the choice of statistical models, and other domains of sleep health.

Weekday time in bed and obesity risk in adolescence

Introduction

Sleep curtailment is associated with obesity in children, but few studies have investigated this relationship in a longitudinal sample of adolescents. The aim of the present study was to examine the longitudinal association between weekday time in bed (TIB) at age 10–13 and overweight at age 16–19.

Methods

Adolescents and their parents (N = 3025 families), participating in a longitudinal population‐based study, completed questionnaires assessing habitual bedtime and wake time on weekdays, weight and height, socioeconomic status (SES), internalizing mental health problems and disturbed eating. Two surveys were administered with a 6‐year interval (T1 and T2). A one‐way analysis of covariance (ANCOVA) was performed examining the association between TIB and weight category 6 years later, with SES, internalizing problems and disturbed eating at baseline entered as covariates. Hierarchical and logistic regression analyses were used to assess TIB at age 10–13 years to as a predictor of body mass index (BMI) standardized deviation scores (SDS) and overweight status at age 16–19 adjusting for the same confounders and baseline BMI.

Results

A linear inverse relationship between TIB at age 10–13 and BMI category at age 16–19 was demonstrated by the ANCOVA, p < 0.001. Shorter TIB was related to higher weight, but the effect size was small (partial eta squared = 0.01). When adjusting for the included baseline confounders in the hierarchical regression model TIB significantly predicted later BMI SDS (β = −0.039, p = 0.02). The adjusted logistic regression model showed that for each hour reduction of TIB at T1 the odds of being overweight/obese at T2 increased with a factor of 1.6.

Conclusion

Shorter TIB was found to be a significant, yet modest, independent predictor of later weight gain in adolescence. The findings implicate that establishing healthy sleep habits should be addressed in prevention and treatment strategies for adolescent obesity.

Severe paediatric obesity and sleep: A mutual interactive relationship!

Childhood severe obesity is a serious, urgent and complex global health problem with long-term co-morbidities. Obstructive sleep-disordered breathing is more common in obese children and adolescents. Increased body mass index is associated with an increase in apnea-hypopnea index. Obstructive sleep apnea leads to a decrease in rapid eye movement sleep, and obese children have been noted to have a decrease in rapid eye movement sleep, leading to weight gain. Short sleep duration and poor sleep quality are associated with childhood obesity and cardiometabolic risks. Public health strategies for obesity prevention should focus more on sleep. Targeting childhood obesity is important in the prevention and management of obstructive sleep-disordered breathing.

Causal Effect of Sleep Duration on Body Weight in Adolescents: A Population-based Study Using a Natural Experiment

Supplemental Digital Content is available in the text.

A large number of observational epidemiologic studies have reported consistent associations between short sleep duration and increased body weight, particularly in children and adolescents. Causal evidence on the effect of sleep duration on body weight is still limited, however.

Mediating effects of body mass index, physical activity, and emotional distress on the relationship between short sleep and cardiovascular disease

The current study investigated the mediating effects of body mass index (BMI), physical activity, and emotional distress on the association between short sleep duration (<7 hours per 24-hour period) and cardiovascular disease (CVD) and risk factors.We used data from the National Health Interview Survey, an ongoing nationally representative cross-sectional study of noninstitutionalized US adults (≥18 years) from 2004 to 2013 (N = 206,049). Participants provided information about anthropometric features (height and weight), sociodemographic factors, health behaviors (smoking and physical activity), emotional distress, and physician-diagnosed health conditions, including hypertension, coronary heart disease, diabetes, heart attack, stroke, kidney disease, and cancer. Structural equation modeling was used to assess the mediating effects of physical activity, BMI, and emotional distress on the relationship between short sleep and CVDs and risk factors (coronary heart disease, hypertension, diabetes, chronic kidney disease, heart attack, and stroke).Of the sample, 54.7% were female, 60.1% identified as white, 17.7% as Hispanic, and 15.4% as black. The mean age of the respondents was 46.75 years (SE = 0.12), with a mean BMI of 27.11 kg/m (SE = 0.02) and approximately 32.5% reported short sleep duration. The main relationship between short sleep and CVD and risk factors was significant (β = 0.08, P < .001), as was the mediated effect via BMI (indirect effect = 0.047, P < .001), emotional distress (indirect effect = 0.022, P < .001), and physical activity (indirect effect = -0.022, P = .035), as well as after adjustment for covariates, including age, race, sex, marital status, and income: short sleep and CVD (B = 0.15; SE = 0.01; P < .001), BMI (B = 0.05; SE = 0.00; P < .001), emotional distress (B = 0.02; SE = 0.00; P < .001), and physical activity (B = 0.01; SE = 0.00; P < .001).Our findings indicate that short sleep is a risk factor for CVD and that the relationship between short sleep and CVD and risk factors may be mediated by emotional distress and obesity, and negatively mediated by physical activity.

Obstructive Sleep Apnea and Sleep Architecture in Adolescents With Severe Obesity: Effects of a 9-Month Lifestyle Modification Program Based on Regular Exercise and a Balanced Diet

STUDY OBJECTIVES

Physical exercise and lifestyle modification are recognized as adjunct therapy for obstructive sleep apnea (OSA) in overweight adults. The objectives of this study were to investigate the effects of long-term physical exercise combined with a balanced diet on sleep architecture, sleep duration, and OSA in adolescents with severe obesity.

METHODS

This interventional study was conducted in a nursing institution. Participants were aged 14.6 ± 1.2 years with obesity (body mass index (BMI) = 40.2 ± 6.5 kg/m2). At admission and at 9 months, participants underwent ambulatory polysomnography and incremental maximal exercise testing to determine cardiorespiratory fitness.

RESULTS

Twenty-four subjects completed the study. Analyses were performed on the whole population and on a subgroup of subjects with OSA (OSA-subgroup). OSA, defined as obstructive apnea-hypopnea index (OAHI) ≥ 2 events/h, was diagnosed in 58.3% of the population. OAHI was only associated with fat mass in males (r = .75, P < .05). At 9 months postintervention, weight loss (-11.1 kg, P < .0001) and improved cardiorespiratory fitness (VO2peak: +4.9 mL/min/kg, P < .001) were found in the whole population. Sleep duration was increased (+34 minutes, P < .05) and sleep architecture was changed with an increase of rapid eye movement sleep (+2.5%, P < .05) and a decrease of stage N3 sleep (-3.1%, P < .001). Similar results were found in the OSA subgroup. However, OAHI remained unchanged (P = .18).

CONCLUSIONS

A combination of supervised aerobic exercise and a balanced diet led to weight loss, improved aerobic capacity, and modified sleep architecture without changes in OSA.

COMMENTARY

A commentary on this article appears in this issue on page 907.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov, Title: Exercise and Venous Compression on Upper Airway Resistance in Obese Teenagers With OSA (OBESOMAC), URL: https://clinicaltrials.gov/ct2/show/NCT02588469, Identifier: NCT02588469.

Past, present, and future: trends in sleep duration and implications for public health

Sleep is important for the physical, social and mental well-being of both children and adults. Over the years, there has been a general presumption that sleep will inevitably decline with the increase in technology and a busy 24-hour modern lifestyle. This narrative review discusses the empirical evidence for secular trends in sleep duration and the implications of these trends.

[Factors associated with poor sleep quality in the Brazilian population ≥ 40 years of age: VIGICARDIO Study]

OBJECTIVE

The prevalence of poor sleep quality in men and women ≥ 40 years old from the VIGICARDIO Study was determined, and sociodemographic, health, lifestyle and social capital factors associated with poor sleep quality were identified.

METHODS

A population-based study conducted in 2011 among 1,058 non-institutionalised individuals randomly selected from Cambé, Paraná State, Brazil. Logistic regression was used to evaluate the association between sleep quality and sociodemographic, health, lifestyle and social capital factors in men and women.

RESULTS

The prevalence of poor sleep quality was 34% in men and 44% in women. Having bad/regular self-rated health status was a factor associated with poor sleep quality in men (OR: 1.79; 95% CI: 1.17-2.72) and women (OR: 2.43; 95% CI: 1.68-3.53). Being obese (OR: 1.67; 95% CI: 1.13-2.46), having depression (OR: 2.09; 95% CI: 1.41-3.13) and presenting temporal orientation difficulties (OR: 1.95; 95% CI: 1.08-3.52) were associated factors in women. Difficulty to understand what is explained (OR: 2.18; 95% CI: 1.16-4.09) and alcohol abuse (OR: 1.85; 95% CI: 1.21-2.83) were associated factors in men.

CONCLUSION

Factors affecting sleep quality are different for men and for women. These factors should be taken into consideration when devising activities that promote good sleep quality, with a view to improving their effectiveness.

The role of sleep in the regulation of body weight

Sleep participates in the regulation of body weight. The amount of sleep and synchronization of the biological clock are both necessary to achieve the energy balance and the secretion of hormones that contribute to weight regulation. In this review, we first reconsider what normal physiological sleep is and what the normative values of sleep are in the general population. Second, we explain how the biological clock regulates the hormones that may be involved in weight control. Third, we provide some recent data on how sleep may be disturbed by sleep disorders or reduced by sleep debt with consequences on weight. Finally, we explore the relationships between sleep debt and obesity.

Is there an association between adolescent sleep restriction and obesity

OBJECTIVE

This is the first prospective study of the reciprocal association between sleep restriction and weight among adolescents. Evidence on sleep duration and obesity in youth is sparse and the results have been equivocal.

METHODS

Data are from a community-based, two-wave cohort study. The setting was a metropolitan area with a population of over 4 million. The cohort consisted of 4175 youths 11-17 at baseline and 3134 of these followed up a year later. Obesity was defined as body mass index >95th percentile for children of the same age and sex. Sleep restriction was defined as 6 or fewer hours of sleep per night on weeknights or on both weekends and weeknights. Covariates examined were age, gender, family income and depression.

RESULTS

Results clearly demonstrated that there was no association between sleep restriction and obesity at baseline. In prospective analyses, sleep restriction did not increase future risk of obesity, nor did obesity increase risk of future sleep restriction.

CONCLUSIONS

These findings call into question previous research based primarily on cross-sectional data suggesting a positive correlation between sleep restriction and obesity. However, the results for adolescents in this study are supported by one study of adolescents and by studies of adults using prospective designs. At this point, there appears to be little evidence for a temporal relation between sleep duration and obesity among adults or adolescents.

[Sleep duration and metabolism]

Sleep duration has gradually diminished during the last decade while obesity and type 2 diabetes have become epidemics. Experimental sleep curtailment leads to increased appetite, hormonal disturbances and, especially, insulin resistance. Numerous epidemiological studies have therefore examined whether habitual short sleep is associated with obesity and type 2 diabetes. A large majority of cross-sectional studies have confirmed an association between short, and also long sleep duration and obesity in adults more than in the elderly. Short sleep is strongly associated to obesity in children and adolescents. Prospective studies, including studies in children, are not conclusive with regard to the effect of short sleep on the incidence of obesity. Both short and long sleep durations are associated with diabetes, but only short sleep duration seems predictive of future diabetes. Insomnia seems to be a strong contributor to short sleep duration but the association of insomnia with obesity is not clear. Insomnia is associated with type 2 diabetes and also predictive of a higher incidence. Other studies have shown that short sleep duration and insomnia are associated with, and sometime predictive of, other components of the metabolic syndrome, especially hypertension and the risk of coronary disease. The treatment of short sleep duration and insomnia with regard to their effects on the metabolic syndrome merits further study.

Successful physical exercise-induced weight loss is modulated by habitual sleep duration in the elderly: results of a pilot study

Although it is widely accepted that physical exercise promotes weight loss, physical exercise alone had been found to result in only marginal weight loss compared to no treatment. Interestingly, both subjective and objective sleep duration have been shown to be negatively correlated to the body mass index (BMI). Despite this growing evidence of a relation between sleep duration and body weight, the role of habitual sleep duration in physical exercise-induced weight loss has not been studied so far. Twenty-two healthy elderly good sleepers aged 61-76 years (mean 68.36 years, 55 % female, BMI mean 25.15 kg/m²) either took part in a 12-week aerobic endurance training (3 × 30 min/week) or in a relaxation control (2 × 45 min/week). The BMI was assessed prior to and after intervention. Subjects maintained sleep logs every morning/evening during the training period, allowing for calculation of habitual sleep duration. Besides a significant main effect of the type of training, a significant interaction of type of training and habitual sleep duration was observed: while after treadmill training subjects who slept less than 7.5 h/night during intervention reduced their BMI by nearly 4 %, a comparable decrease in the BMI was found neither in subjects who slept more than 7.5 h nor after relaxation training independent of sleep duration. Sleep duration itself did not change in any group. Although results should be interpreted with caution due to the small sample size, this is the first study to indicate that physical exercise might compensate for disturbed body weight regulation associated with short sleep duration.

Sleep and Food Choice in a Dutch Student Population

Background: The increased risk of obesity among short sleepers is most likely explained by increased energy intake. However, food intake could not only be altered quantitavely but also qualitatively. Therefore, we performed a correlational analysis on self-reported food intake and sleep in 51 students from Maastricht and surroundings.

Results: Students that slept longer had a lower caloric intake: ρ = −0.378, p = 0.006, the amount of calories consumed per minute awake remaining relatively stable. However, sleep duration did not correlate with intake of percentage fat, saturated fat, carbohydrates or protein. Average energy intake during the reported breakfasts, lunches, dinners or snacks separately did also not correlate with total sleep time.

Conclusion: It seems that shorter sleep correlates with absolute caloric intake, but not with the intake of specific dietary components.

Human REM sleep: influence on feeding behaviour, with clinical implications

Rapid eye movement (REM) sleep shares many underlying mechanisms with wakefulness, to a much greater extent than does non-REM, especially those relating to feeding behaviours, appetite, curiosity, exploratory (locomotor) activities, as well as aspects of emotions, particularly 'fear extinction'. REM is most evident in infancy, thereafter declining in what seems to be a dispensable manner that largely reciprocates increasing wakefulness. However, human adults retain more REM than do other mammals, where for us it is most abundant during our usual final REM period (fREMP) of the night, nearing wakefulness. The case is made that our REM is unusual, and that (i) fREMP retains this 'dispensability', acting as a proxy for wakefulness, able to be forfeited (without REM rebound) and substituted by physical activity (locomotion) when pressures of wakefulness increase; (ii) REM's atonia (inhibited motor output) may be a proxy for this locomotion; (iii) our nocturnal sleep typically develops into a physiological fast, especially during fREMP, which is also an appetite suppressant; (iv) REM may have 'anti-obesity' properties, and that the loss of fREMP may well enhance appetite and contribute to weight gain ('overeating') in habitually short sleepers; (v) as we also select foods for their hedonic (emotional) values, REM may be integral to developing food preferences and dislikes; and (vii) REM seems to have wider influences in regulating energy balance in terms of exercise 'substitution' and energy (body heat) retention. Avenues for further research are proposed, linking REM with feeding behaviours, including eating disorders, and effects of REM-suppressant medications.

Obesity in urban women: associations with sleep and sleepiness, fatigue and activity

BACKGROUND

African-American women (AAW) have the highest prevalence of obesity and therefore are at greater risk for obesity-related symptoms and diseases. Obese individuals frequently report poorer sleep quality, more daytime sleepiness, more severe fatigue, and higher physical inactivity than normal weight individuals. The relationships among these variables have not been well-characterized in obese, urban-dwelling, AAW.

METHODS

This descriptive, correlational study examined the relationships among sleep quality, daytime sleepiness, fatigue, level of physical activity, and body mass index (BMI) in AAW living in an urban setting. A convenience sample of 69 young adult women with a BMI of greater than 30 kg/m(2) completed measures of sleep quality, sleepiness, fatigue severity, sense of community, and physical activity. Further analysis was done to determine if any of the study variables predicted level of physical activity.

FINDINGS

There was a strong and significant correlation between BMI and overall fatigue severity and a significant, negative correlation between BMI and physical activity performance. BMI was significantly correlated with sleep latency but not global sleep quality. There were significant relationships between fatigue severity and poorer global sleep quality and daytime sleepiness. Multiple regression analysis showed BMI and age accounted for a significant amount of the variance in physical activity.

CONCLUSIONS

Higher BMI was associated with significant fatigue. Fatigue severity was associated with poorer global sleep quality, daytime sleepiness, and a sense of community. Higher BMI may be a barrier to having an active lifestyle.

Severe chronic insomnia is not associated with higher body mass index

Short sleep duration is widely considered to be a risk factor for weight gain, suggesting that patients suffering from sleep disorders are a risk group. Despite some positive preliminary data on patients with organic sleep disorders, empirical evidence for an increased body mass index in patients with insomnia is scarce. Two-hundred and thirty-three patients with a confirmed diagnosis of severe and chronic insomnia without co-morbidity showing objectively impaired sleep quality were compared with respect to their body mass index with control data derived from a representative population survey matched in gender and age. As a result, patients with insomnia showed a lower body mass index (23.8 kg m(-2) versus 27.1 kg m(-2) ; P < 0.0005). Our findings suggest that patients with chronic insomnia do not exhibit overweight. These data are a valuable educational tool to calm patients' fears about the consequences of insomnia, and contribute to the understanding of chronically disturbed sleep and weight regulation.

Objective sleep structure and cardiovascular risk factors in the general population: the HypnoLaus Study

STUDY OBJECTIVES

To evaluate the association between objective sleep measures and metabolic syndrome (MS), hypertension, diabetes, and obesity.

DESIGN

Cross-sectional study.

SETTING

General population sample.

PARTICIPANTS

There were 2,162 patients (51.2% women, mean age 58.4 ± 11.1).

INTERVENTIONS

Patients were evaluated for hypertension, diabetes, overweight/obesity, and MS, and underwent a full polysomnography (PSG).

MEASUREMENTS AND RESULTS

PSG measured variables included: total sleep time (TST), percentage and time spent in slow wave sleep (SWS) and in rapid eye movement (REM) sleep, sleep efficiency and arousal index (ArI). In univariate analyses, MS was associated with decreased TST, SWS, REM sleep, and sleep efficiency, and increased ArI. After adjustment for age, sex, smoking, alcohol, physical activity, drugs that affect sleep and depression, the ArI remained significantly higher, but the difference disappeared in patients without significant sleep disordered breathing (SDB). Differences in sleep structure were also found according to the presence or absence of hypertension, diabetes, and overweight/obesity in univariate analysis. However, these differences were attenuated after multivariate adjustment and after excluding subjects with significant SDB.

CONCLUSIONS

In this population-based sample we found significant associations between sleep structure and MS, hypertension, diabetes, and obesity. However, these associations were cancelled after multivariate adjustment. We conclude that normal variations in sleep contribute little if any to MS and associated disorders.

Sleep and energy intake in early childhood

Background And Objectives:

Shorter sleep is associated with higher weight in children, but little is known about the mechanisms. The aim of this study was to test the hypothesis that shorter sleep was associated with higher energy intake in early childhood.

Methods:

Participants were 1303 families from the Gemini twin birth cohort. Sleep duration was measured using the Brief Infant Sleep Questionnaire when the children were 16 months old. Total energy intake (kcal per day) and grams per day of fat, carbohydrate and protein were derived from 3-day diet diaries completed by parents when children were 21 months old.

Results:

Shorter nighttime sleep was associated with higher total energy intake (P for linear trend=0.005). Children sleeping <10 h consumed around 50 kcal per day more than those sleeping 11–<12 h a night (the optimal sleep duration for children of this age). Differences in energy intake were maintained after adjustment for confounders. As a percentage of total energy intake, there were no significant differences in macronutrient intake by sleep duration. The association between sleep and weight was not significant at this age (P=0.13).

Conclusions:

This study provides the first evidence that shorter nighttime sleep duration has a linear association with higher energy intake early in life. That the effect is observed before emergence of associations between sleep and weight indicates that differences in energy intake may be a mechanism through which sleep influences weight gain.

Impulsivity and genetic variants in DRD2 and ANKK1 moderate longitudinal associations between sleep problems and overweight from ages 5 to 11

OBJECTIVE

Short sleep duration and sleep problems increase risks of overweight and weight gain. Few previous studies have examined sleep and weight repeatedly over development. This study examined the associations between yearly reports of sleep problems and weight status from ages 5 to 11. Although, previous studies have shown that inter-individual differences moderate the effect of short sleep duration on weight, it is not known whether inter-individual differences also moderate the effect of sleep problems on weight. We tested how the longitudinal associations between sleep problems and weight status were moderated by impulsivity and genetic variants in DRD2 and ANKK1.

DESIGN

Seven-year longitudinal study.

PARTICIPANTS

A total of 567 children from the Child Development Project for the analysis with impulsivity and 363 for the analysis with genetic variants.

MEASUREMENTS AND RESULTS

Sleep problems and weight status were measured by mothers' reports yearly. Impulsivity was measured by teachers' reports yearly. Six single-nucleotide polymorphisms located in DRD2 and ANKK1 were genotyped. Data were analyzed using multilevel modeling. Higher average levels of sleep deprivation across years were associated with greater increases in overweight (P=0.0024). Sleep problems and overweight were associated at both within-person across time (P<0.0001) and between-person levels (P<0.0001). Impulsivity and two polymorphisms, rs1799978 and rs4245149 in DRD2, moderated the association between sleep problems and overweight; the association was stronger in children who were more impulsive (P=0.0022), in G allele carriers for rs1799978 (P=0.0007) and in A allele carriers for rs4245149 (P=0.0002).

CONCLUSIONS

This study provided incremental evidence for the influence of sleep problems on weight. Findings of DRD2, ANKK1 and impulsivity are novel; they suggest that reward sensitivity and self-regulatory abilities might modulate the influences of sleep on weight gain. The analysis of polymorphisms was restricted to European Americans and hence the results might not generalize to other populations.

Thyroid hormone signaling and homeostasis during aging

Studies in humans and in animal models show negative correlations between thyroid hormone (TH) levels and longevity. TH signaling is implicated in maintaining and integrating metabolic homeostasis at multiple levels, notably centrally in the hypothalamus but also in peripheral tissues. The question is thus raised of how TH signaling is modulated during aging in different tissues. Classically, TH actions on mitochondria and heat production are obvious candidates to link negative effects of TH to aging. Mitochondrial effects of excess TH include reactive oxygen species and DNA damage, 2 factors often considered as aging accelerators. Inversely, caloric restriction, which can retard aging from nematodes to primates, causes a rapid reduction of circulating TH, reducing metabolism in birds and mammals. However, many other factors could link TH to aging, and it is these potentially subtler and less explored areas that are highlighted here. For example, effects of TH on membrane composition, inflammatory responses, stem cell renewal and synchronization of physiological responses to light could each contribute to TH regulation of maintenance of homeostasis during aging. We propose the hypothesis that constraints on TH signaling at certain life stages, notably during maturity, are advantageous for optimal aging.

Prolonged sleep fragmentation of mice exacerbates febrile responses to lipopolysaccharide

BACKGROUND

Sleep disruption is a frequent occurrence in modern society. Whereas many studies have focused on the consequences of total sleep deprivation, few have investigated the condition of sleep disruption.

NEW METHOD

We disrupted sleep of mice during the light period for 9 consecutive days using an intermittently rotating disc.

RESULTS

Electroencephalogram (EEG) data demonstrated that non-rapid eye movement (NREM) sleep was severely fragmented and REM sleep was essentially abolished during the 12h light period. During the dark period, when sleep was not disrupted, neither NREM sleep nor REM sleep times differed from control values. Analysis of the EEG revealed a trend for increased power in the peak frequency of the NREM EEG spectra during the dark period. The fragmentation protocol was not overly stressful as body weights and water consumption remained unchanged, and plasma corticosterone did not differ between mice subjected to 3 or 9 days of sleep disruption and home cage controls. However, mice subjected to 9 days of sleep disruption by this method responded to lipopolysaccharide with an exacerbated febrile response.

COMPARISON WITH EXISTING METHODS

Existing methods to disrupt sleep of laboratory rodents often subject the animal to excessive locomotion, vibration, or sudden movements. This method does not suffer from any of these confounds.

CONCLUSIONS

This study demonstrates that prolonged sleep disruption of mice exacerbates febrile responses to lipopolysaccharide. This device provides a method to determine mechanisms by which chronic insufficient sleep contributes to the etiology of many pathologies, particularly those with an inflammatory component.

Lower limb lymphedema in gynecological cancer survivors--effect on daily life functioning

PURPOSE

Lower limb lymphedema (LLL) is a common condition after pelvic cancer treatment but few studies have evaluated its effect on the quality of life and its consequences on daily life activities among gynecological cancer survivors.

METHODS

We identified a cohort of 789 eligible women, treated with pelvic radiotherapy alone or as part of combined treatment of gynecological cancer, from 1991 to 2003 at two departments of gynecological oncology in Sweden. As a preparatory study, we conducted in-depth interviews with gynecological cancer survivors and constructed a study-specific questionnaire which we validated face-to-face. The questionnaire covered physical symptoms originating in the pelvis, demographic, psychological, and quality of life factors. In relation to the lymph system, 19 questions were asked.

RESULTS

Six hundred sixteen (78 %) gynecological cancer survivors answered the questionnaire and participated in the study. Thirty-six percent (218/606) of the cancer survivors reported LLL. Overall quality of life was significantly lower among cancer survivors with LLL. They were also less satisfied with their sleep, more worried about recurrence of cancer, and more likely to interpret symptoms from the body as recurrence. Cancer survivors reported that LLL kept them from physical activity (45 %) and house work (29 %) and affected their ability to partake in social activities (27 %) or to meet friends (20 %).

CONCLUSION

Lower limb lymphedema has a negative impact on quality of life among gynecological cancer survivors, affecting sleep and daily life activities, yet only a few seek professional help.

Effects of three weeks of mild sleep restriction implemented in the home environment on multiple metabolic and endocrine markers in healthy young men

OBJECTIVES

Evidence for a causal relationship between sleep-loss and metabolism is derived primarily from short-term sleep deprivation studies in the laboratory. The objective of this study was to investigate whether small changes in sleep duration over a three week period while participants are living in their normal environment lead to changes in insulin sensitivity and other metabolic parameters.

METHODS

Nineteen healthy, young, normal-weight men were randomised to either sleep restriction (habitual bedtime minus 1.5h) or a control condition (habitual bedtime) for three weeks. Weekly assessments of insulin sensitivity by hyperinsulinaemic-euglycaemic clamp, anthropometry, vascular function, leptin and adiponectin were made. Sleep was assessed continuously using actigraphy and diaries.

RESULTS

Assessment of sleep by actigraphy confirmed that the intervention reduced daily sleep duration by 01:19 ± 00:15 (SE; p<0.001). Sleep restriction led to changes in insulin sensitivity, body weight and plasma concentrations of leptin which varied during the three week period. There was no effect on plasma adiponectin or vascular function.

CONCLUSIONS

Even minor reductions in sleep duration lead to changes in insulin sensitivity, body weight and other metabolic parameters which vary during the exposure period. Larger and longer longitudinal studies of sleep restriction and sleep extension are warranted.

Association between sleep duration, weight gain, and obesity for long period

BACKGROUND

Although previous studies showed the long-term effects of sleep duration on risk of weight gain, Western tends to gain weight irrespective of sleep duration over a long period. Conversely, it is showed that body mass index (BMI) decreases during a long period in Japanese and thus, the long-term effect of sleep duration on weight gain and obesity is still unclear in Asia.

METHODS

We followed up 13,629 participants aged 40-79years and prospectively collected data from 1995 to 2006. We divided the participants into five groups according to their self-reported sleep duration: ⩽5h (short sleep), 6h, 7h (reference), 8h, and ⩾9h (long sleep). The main outcome was ⩾5kg weight gain or BMI⩾25kg/m(2) (obesity). We used logistic regression analyses to derive odds ratios (ORs) and 95% confidence intervals (CIs), adjusted for several confounding factors.

RESULTS

We observed no association between sleep duration and risk of ⩾5kg weight gain and obesity. After stratification by BMI, long sleepers had a significantly increased risk of ⩾5kg weight gain (OR: 1.36, 95%CI: 1.09-1.70) in obese participants.

CONCLUSIONS

Among community-dwelling Japanese, only obese long sleepers have a significantly increased long-term risk of ⩾5kg weight gain.

Short sleep duration and its association with energy metabolism

A growing body of observational evidence suggests that short sleep duration is a risk factor for the development of obesity. Although increased energy intake is the most prevailing causal explanation for this association, we should also consider possible effects on energy metabolism to understand fully the potential impact of short sleep duration on the regulation of energy balance. We performed a search of the literature from 1970 to 2011, including original papers, investigating the relation between short sleep and energy metabolism in animals and humans. Although the limited number of experimental studies in humans precludes any definitive conclusions about causality, short sleep duration does not seem to substantially affect total daily energy expenditure, nor is there sufficient evidence in support of any meaningful effect of restricted sleep on the specific components of energy metabolism (i.e. resting metabolic rate, intentional as well as unintentional physical activity, diet-induced thermogenesis, and substrate utilization). As studies on rats suggest that other factors that can potentially influence energy metabolism could be affected (i.e. hormonal systems and thermoregulation), we included these factors in our literature search and found some indications in support of an up-regulation of thyroid hormones and glucocorticoids as well as increased heat dissipation following total or severe sleep deficit. Although we found some evidence also in humans that suggests a possible effect on energy metabolism, the limitations of the studies make it difficult to draw conclusions on the effect of short sleep on energy metabolism under relevant free living conditions. To explore this area further, more studies using suitable methodology under relevant conditions to mimic real-life situations are needed.

The night-eating syndrome and obesity

The rising prevalence of obesity is a global concern. Eating behaviour and circadian rhythm are proving to be important factors in the aetiology of obesity. The night-eating syndrome (NES) is characterized by increased late-night eating, insomnia, a depressed mood and distress. It is evident that prevalence is higher among weight-related populations than the general community. The exact relationship between this syndrome and obesity remains unclear. The reasons for the discrepancies found in the literature likely include varying diagnostic criteria and a wide range of study population characteristics. NES does not always lead to weight gain in thus certain individuals may be susceptible to night-eating-related weight gain. Weight loss through surgical and behavioural treatments has shown success in diminishing symptoms. The increasing literature associating obesity with circadian imbalances strengthens the link between the NES and obesity. Circadian genes may play a role in this syndrome. This review will examine different aspects of obesity in the context of the NES.

Update on energy homeostasis and insufficient sleep

Driven by the demands and opportunities of modern life, many people habitually sleep less than 6 h a night. In the sleep clinic, chronic sleep restriction is recognized by the diagnosis of insufficient sleep syndrome (ICSD-9, 307.49-4), which is receiving increased scrutiny as a potential risk to metabolic health. Its relevance for the practicing endocrinologist is highlighted by a stream of epidemiological data that show an association of insufficient sleep with increased incidence of obesity and related morbidities. A central theme of this update is the notion that sleep loss incurs additional metabolic cost, which triggers a set of neuroendocrine, metabolic, and behavioral adaptations aimed at increasing food intake and conserving energy. Although this coordinated response may have evolved to offset the metabolic demands of extended wakefulness in natural habitats with limited food availability, it can be maladaptive in the context of a modern environment that allows many to overeat while maintaining a sedentary lifestyle without sufficient sleep. Importantly, such sleep loss-related metabolic adaptation may undermine the success of behavioral interventions based on reduced caloric intake and increased physical activity to lower metabolic risk in obesity-prone individuals. This emerging perspective is based on data from recently published human interventional studies and requires further experimental support. Nevertheless, it now seems prudent to recommend that overweight and obese individuals attempting to reduce their caloric intake and maintain increased physical activity should obtain adequate sleep and, if needed, seek effective treatment for any coexisting sleep disorders.

Risk factors associated with nephrolithiasis: a case-control study in China

Nephrolithiasis is a multifactorial disease. The authors conducted a case-control study in China to explore its associated risk factors. A total of 725 nephrolithiasis patients and 553 controls were asked to complete a questionnaire that asked for information about psychological, behavioral, and dietary factors along with a physical and blood biochemical examination. For men, higher education was negatively associated with nephrolithiasis (odds ratio [OR] = 0.6; 95% confidence interval [CI] = 0.4-1.0), whereas hypso-waist-to-hip ratio (hypso-WHR), defined as WHRs >0.9 for men and >0.8 for women (OR = 2.2; 95% CI = 1.4-3.4); overexercise (OR = 2.1; 95% CI = 1.3-3.5); and having experienced negative life events (OR = 2.2; 95% CI = 1.2-4.1) were positively associated with nephrolithiasis. For women, higher fluid intake was negatively associated with nephrolithiasis (OR = 0.6; 95% CI = 0.3-0.9), and abnormal status of blood pressure (BP) and blood lipids was positively associated with nephrolithiasis. Varied factors were related to differences in nephrolithiasis occurrence between genders. Besides taking enough fluids, maintaining a normal metabolic status, avoiding overexercise, and reducing BP might be beneficial in preventing nephrolithiasis.

Serotonin conflict in sleep-feeding

Short sleep duration has been suggested to be a risk factor for weight gain and adiposity. Serotonin (5-HT) substantially contributes to the regulation of sleep and feeding behavior. Although 5-HT predominately promotes waking and satiety, the effects of 5-HT depend on 5-HT receptor function. The 5-HT1A, 5-HT1B, 5-HT2A, 5-HT2C, 5-HT6, and 5-HT7 receptors reportedly contribute to sleep-waking regulation, whereas the 5-HT1B and 5-HT2C receptors contribute to the regulation of satiety. The 5-HT1B and 2C receptors may therefore be involved in the regulation of sleep-feeding. In genetic studies, 5-HT1B receptor mutant mice display greater amounts of rapid eye movement sleep (REMS) than wild-type mice, while displaying no effects on waking or slow wave sleep (SWS). On the other hand, 5-HT2C receptor mutant mice exhibit increased wakefulness and decreased SWS, without any effect on REMS. Moreover, the 5-HT2C receptor mutants display leptin-independent hyperphagia, leading to a middle-aged onset of obesity, whereas 5-HT1B receptor mutants do not display any effect on food intake. Thus, the genetic deletion of 5-HT2C receptors results in sleep loss-associated hyperphagia, leading to the late onset of obesity. This is a quite different pattern of sleep-feeding behavior than is observed in disturbed leptin signaling, which displays an increase in sleep-associated hyperphagia. In pharmacologic studies, 5-HT1B and 5-HT2C receptors upregulate wakefulness and downregulate SWS, REMS, and food intake. These findings suggest that 5-HT1B/2C receptor stimulation induces sleep loss-associated anorexia. Thus, the central 5-HT regulation of sleep-feeding can be dissociated. Functional hypothalamic proopiomelanocortin and orexin activities may contribute to the dissociated 5-HT regulation.

Sleep and metabolic function

Evidence for the role of sleep on metabolic and endocrine function has been reported more than four decades ago. In the past 30 years, the prevalence of obesity and diabetes has greatly increased in industrialized countries, and self-imposed sleep curtailment, now very common, is starting to be recognized as a contributing factor, alongside with increased caloric intake and decreased physical activity. Furthermore, obstructive sleep apnea, a chronic condition characterized by recurrent upper airway obstruction leading to intermittent hypoxemia and sleep fragmentation, has also become highly prevalent as a consequence of the epidemic of obesity and has been shown to contribute, in a vicious circle, to the metabolic disturbances observed in obese patients. In this article, we summarize the current data supporting the role of sleep in the regulation of glucose homeostasis and the hormones involved in the regulation of appetite. We also review the results of the epidemiologic and laboratory studies that investigated the impact of sleep duration and quality on the risk of developing diabetes and obesity, as well as the mechanisms underlying this increased risk. Finally, we discuss how obstructive sleep apnea affects glucose metabolism and the beneficial impact of its treatment, the continuous positive airway pressure. In conclusion, the data available in the literature highlight the importance of getting enough good sleep for metabolic health.