Cross-sectional associations between measures of sleep and markers of glucose metabolism among subjects with and without diabetes: the Coronary Artery Risk Development in Young Adults (CARDIA) Sleep Study

The prevalence of impaired glucose regulation in psychiatric patients with sleep disorders and its relationship with altered hypothalamopituitary-adrenal and hypothalamopituitary-thyroid axis activity

BACKGROUND

Sleep restriction, an important symptom of psychiatric diseases, is associated with adverse effects on glucose regulation, but few studies have examined its association with impaired glucose regulation and altered hypothalamic activity. Our study was designed to evaluate the sleep duration, fasting glucose, tolerance glucose, and concentration of plasma insulin; to assess the function of both the hypothalamopituitary-thyroid (HPT) and hypothalamopituitary-adrenal (HPA) axis; and to investigate the relationship of altered hypothalamic function with glucose metabolism in psychiatric patients with a sleep disorders.

METHODS

From January 2010 to December 2011, 324 women (64.7%) and 177 men (35.32%) with a diagnosis of a sleep disorder participated in our cross-sectional study in the psychiatric outpatient department of the West China Hospital of Sichuan University. Results from 75-g glucose tolerance tests, insulin-releasing tests, morning (8:00 am) serum cortisol, and thyroid-stimulating hormone (TSH) (TT3, TT4, FT3, FT4) were collected, as well as body mass index and waist-hip ratio to assess the prevalence of impaired glucose regulation and function of the HPA and HPT axis. Sleep quality was assessed through self-reported questionnaires.

RESULTS

There were 301 patients previously diagnosed with an anxiety disorder (78%), and 200 patients previously diagnosed with depression and other psychiatric diseases (22%). Crude prevalence rates were 15.0% for diabetes mellitus (DM), 11.6% for impaired glucose tolerance, 15.8% for impaired fasting glucose, and 11.6% for impaired glucose regulation (impaired glucose tolerance [IGT]+impaired fasting glucose [IFG]). Total prevalence of impaired glucose regulation in patients with a sleep disorder was 48.8%. Mean cortisol level was 463.5±178.8 nmol/L, and the cortisol concentration at 8:00 am was significantly associated with a higher prevalence of impaired glucose regulation and insulin resistance. TSH values above 2.5 mU/L accounted for over 58% and were significantly associated with insulin resistance.

CONCLUSIONS

These results partially confirm that a high level of cortisol and an increased activity of the HPT axis are associated with impaired glucose regulation. Therefore, as a pathophysiologic event abnormal activity of the hypothalamic function of psychiatric patients with sleep disorders could be viewed as a potential risk factor for increasing incidence of DM.

Chronobiology, endocrinology, and energy- and food-reward homeostasis

Energy- and food-reward homeostasis is the essential component for maintaining energy balance and its disruption may lead to metabolic disorders, including obesity and diabetes. Circadian alignment, quality sleep and sleep architecture in relation to energy- and food-reward homeostasis are crucial. A reduced sleep duration, quality sleep and rapid-eye movement sleep affect substrate oxidation, leptin and ghrelin concentrations, sleeping metabolic rate, appetite, food reward, hypothalamic-pituitary-adrenal (HPA)-axis activity, and gut-peptide concentrations, enhancing a positive energy balance. Circadian misalignment affects sleep architecture and the glucose-insulin metabolism, substrate oxidation, homeostasis model assessment of insulin resistance (HOMA-IR) index, leptin concentrations and HPA-axis activity. Mood disorders such as depression occur; reduced dopaminergic neuronal signaling shows decreased food reward. A good sleep hygiene, together with circadian alignment of food intake, a regular meal frequency, and attention for protein intake or diets, contributes in curing sleep abnormalities and overweight/obesity features by preventing overeating; normalizing substrate oxidation, stress, insulin and glucose metabolism including HOMA-IR index, and leptin, GLP-1 concentrations, lipid metabolism, appetite, energy expenditure and substrate oxidation; and normalizing food reward. Synchrony between circadian and metabolic processes including meal patterns plays an important role in the regulation of energy balance and body-weight control. Additive effects of circadian alignment including meal patterns, sleep restoration, and protein diets in the treatment of overweight and obesity are suggested.

The relationship between impaired fasting glucose and self-reported sleep quality in a Chinese population

OBJECTIVE

Decreased sleep quality and duration predicts the development of type 2 diabetes. Prediabetes is an established risk factor for type 2 diabetes and cardiovascular disease. However, there is limited research on the association between prediabetes and sleep quality. The aim of this study is to investigate this relationship in a Chinese population.

METHODS

Subjects were recruited from the Prevention Health Center of National Cheng Kung University Hospital. Anthropometric data and metabolic parameters were measured. The diagnoses of impaired fasting glucose (IFG), impaired glucose tolerance (IGT) and diabetes followed the recommendations of the American Diabetes Association. Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI).

RESULTS

A total of 1805 subjects with normal glucose tolerance (NGT, n = 1217), IFG (n = 118), IGT (n = 287), IFG+IGT (n = 80) and newly diagnosed diabetes (NDD, n = 103) were recruited. The global PSQI scores were 6·07 ± 2·44, 6·74 ± 3·23, 6·91 ± 3·51, 6·74 ± 2·26 and 7·16 ± 3·49 in subjects with NGT, IFG, IGT, IFG+IGT and NDD, respectively. Multivariate linear regression analysis showed that female gender, smoking, IGT, IFG+IGT and NDD, but not IFG, were independent determinants of global PSQI score. Multivariate logistic regression analysis showed that female gender, IGT, IFG+IGT and NDD, but not IFG, were predictors of poor sleepers.

CONCLUSIONS

Subjects with prediabetes and NDD had a significantly higher global PSQI score than those with NGT. Furthermore, female gender, smoking, IGT, IFG+IGT and NDD, but not IFG, were significantly associated with poor sleep quality independent of cardiometabolic risk factors in a Chinese population.

The association between self-reported sleep quality and overweight in a Chinese population

OBJECTIVE

Sleep quality and obesity are associated with type 2 diabetes, hypertension, and metabolic syndrome. However, there is limited research on the association between sleep quality and obesity, and thus the aim of this study is to investigate this relationship in a Chinese population.

DESIGN AND METHODS

Subjects were recruited from the Prevention Health Center of National Cheng Kung University Hospital. Anthropometric data and metabolic parameters were measured. Being overweight or obese was defined according to the recommendations of the Department of Health in Taiwan. Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI).

RESULTS

Of the total 2,803 subjects, 1,059 were classified as normal weight, 1,127 were overweight, and 617 were obese. The global PSQI score were 6.30 ± 2.56, 6.61 ± 2.96, and 7.02 ± 2.95 in subjects who were normal weight, overweight, and obese, respectively (test for trend, P < 0.001). Of the variables tested in the multivariate linear regression model, female gender, being overweight, obesity, sleep duration, and alcohol drinking were significantly associated with global PSQI scores, and in the multivariate logistic regression model, female gender, being overweight, obesity, and sleep duration were independent predictors of poor sleepers after controlling for age, gender, BMI or different weight statuses, sleep duration, alcohol drinking, smoking, habitual exercise, hypertension, newly diagnosed diabetes, total cholesterol, high-density lipoprotein, triglyceride, estimated glomerular filtration rate, and alanine aminotransferase.

CONCLUSIONS

In conclusion, female gender, being overweight, obesity, and sleep duration were associated with poor sleep quality independent of cardiometabolic risk factors. In clinical practice, subjects who are obese, or even only overweight, should be evaluated for the presence of sleep disturbance.

Impact of sleep duration on obesity and the glycemic level in patients with type 2 diabetes: the Fukuoka Diabetes Registry

OBJECTIVE

Few studies are currently available regarding the influence of sleep duration on glycemic control in diabetic patients. The objective of the current study was to examine the relationship between sleep duration, obesity, and the glycemic level in type 2 diabetic patients.

RESEARCH DESIGN AND METHODS

A total of 4,870 Japanese type 2 diabetic patients aged ≥20 years were divided into six groups according to their self-reported sleep duration: less than 4.5 h, 4.5-5.4 h, 5.5-6.4 h, 6.5-7.4 h, 7.5-8.4 h, and more than 8.5 h. The associations of sleep duration with obesity and the HbA(1c) levels were examined in a cross-sectional manner.

RESULTS

The HbA(1c) levels showed a quadratic association with sleep duration; namely, a shorter or longer sleep duration was associated with a higher level compared with a sleep duration of 6.5-7.4 h (P for quadratic trend <0.001). This association remained significant after adjusting for potential confounders, including the total energy intake and depressive symptoms. Furthermore, additional adjustments for obesity, which also showed a U-shaped relationship with sleep duration, did not attenuate the U-shaped sleep-HbA(1c) association. A significant interaction between sleep duration and age or the use of insulin was observed for the HbA(1c) levels.

CONCLUSIONS

Sleep duration was shown to have U-shaped associations with obesity and the HbA(1c) levels in type 2 diabetic patients, independent of potential confounders, and therefore may be an important modifiable factor for the clinical management of patients with type 2 diabetes.

Disturbed subjective sleep in Chinese females with type 2 diabetes on insulin therapy

Objectives

The aim of this study is to investigate the prevalence and determine the possible risk factors of poor sleep quality in Chinese type 2 diabetes patients with insulin treatment.

Methods

140 type 2 diabetes patients with insulin treatments were enrolled in our study. General characteristics and laboratory testing such glycosylated hemoglobin A1c (HbA1c), fasting plasma glucose (FPG), post-prandial plasma glucose (PPG) were measured. Every patient completed Chinese version of Pittsburgh Sleep Quality Index (PSQI) questionnaire. PSQI global score>5 was defined as poor sleep quality.

Results

Global PSQI score was significantly higher in female type 2 diabetes patients with insulin treatment than male (7.52 vs 6.08, P<0.05). After adjusting for age, BMI, FPG, PPG, HbA1c and duration of diabetes, female is still an independent risk factor for poor sleep quality [OR = 2.55, 95% confidence interval (CI) = 1.24–5.27, P = 0.01].

Conclusion

The results suggest that we found poor sleep quality in female Chinese type 2 diabetes patients with insulin treatment and these findings may contribute to sleep disorder control in female type 2 diabetes.

The association between self-reported sleep quality and metabolic syndrome

Objectives

Short and long sleep duration are associated with metabolic syndrome. However, there is limited research on the association between sleep quality and metabolic syndrome, and thus the aim of this study is to investigate this relationship.

Materials and Methods

The cross-sectional baseline data were collected from the decoded database of the Prevention Health Center of National Cheng Kung University Hospital from 2002 to 2006. The diagnosis of metabolic syndrome was according to the statement of the American Heart Association/National Heart, Lung, and Blood Institute. Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI). A higher global PSQI score indicates poorer sleep quality, and a global PSQI score greater than five differentiates poor from good sleepers.

Results

Of the 3,435 subjects recruited, 899 (26.2%) had metabolic syndrome. Subjects with metabolic syndrome had higher PSQI and prevalence of poor sleepers than those without metabolic syndrome. The multivariate lineal regression analysis showed that female gender, metabolic syndrome, sleep duration, snoring, alcohol drinking, and habitual exercise were independent predictors of PSQI. When substituting metabolic syndrome with the five components, hyperglycemia and low high-density lipoprotein cholesterol (HDL-C) were positively associated with PSQI. The multivariate logistic regression analyses showed that female gender, metabolic syndrome, sleep duration, and snoring were independently associated with being poor sleepers. Of the five components, only low HDL-C was an independent predictor of being poor sleepers.

Conclusions

Subjects with metabolic syndrome have higher global PSQI scores and a higher risk of being poor sleepers. Of the five components of metabolic syndrome, hyperglycemia and low HDL-C are independently associated with the global PSQI scores, while low HDL-C is an independent predictor of being poor sleepers.

Association between Sleep Disruption and Levels of Lipids in Caucasians with Type 2 Diabetes

Aim. To investigate the association between sleep quality and duration with lipid and glycaemic control in Caucasian subjects with type 2 diabetes. Methods. Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI) in 114 type 2 diabetes (T2DM) subjects. Comparisons were made between subjects with different sleep quality and sleep duration. Hierarchical multiple regression analyses were used to determine contributors to metabolic parameters. Results. Subjects with poor sleep quality (PQ; PSQI ≥ 6) had higher systolic blood pressure, glycated haemoglobin, urine albumin : creatinine ratio (UAC), total cholesterol (TC), and triglycerides (TG) (P < 0.05 for all) compared to those with good sleep quality (GQ; PSQI ≤ 5). Long sleep duration (LSD) subjects had higher TC and short sleep duration (SSD) subjects had higher TG compared to those with medium sleep duration. Sleep duration and PSQI score were independent predictors of TC and low-density lipoprotein cholesterol (LDL), contributing to 14.0% and 6.1% of the total variance, respectively. Conclusions. In this Caucasian T2DM population, PQ is associated with adverse cardiovascular risk markers, and long and short sleep disruptions have an independent negative impact on lipids. Sleep assessment should be included as part of a diabetes clinic review.

Improving sleep hygiene behavior in adults living with HIV/AIDS: a randomized control pilot study of the SystemCHANGE(TM)-HIV intervention

AIM

The aim of this study was to test the feasibility of a novel, evidence-based intervention SystemCHANGE-HIV on sleep outcomes.

BACKGROUND

Insomnia and sleep disturbances affect an estimated 74% of people living with HIV (PLWH) and is a distressing consequence of HIV disease.

METHODS

We conducted a two-group randomized control study with 40 PLWH. Outcomes included change in: sleep duration, sleep fragmentation index, sleep efficiency, and self-reported sleep quality.

RESULTS

Participants rated the intervention as highly feasible. The intervention group experienced a 10minute/night increase in sleep time, a 2.3%-point increase in sleep efficiency, a 2.0%-point decrease in sleep fragmentation, relative to the control group, based on the model estimates of the treatment effect.

CONCLUSIONS

A behavioral change intervention focusing on sleep is feasible in PLWH. The intervention group had improved sleep compared to the control group. Future work should test the efficacy of a refined SystemCHANGE-HIV on sleep.

Circadian topology of metabolism

Biological clocks are genetically encoded oscillators that allow organisms to anticipate changes in the light-dark environment that are tied to the rotation of Earth. Clocks enhance fitness and growth in prokaryotes, and they are expressed throughout the central nervous system and peripheral tissues of multicelled organisms in which they influence sleep, arousal, feeding and metabolism. Biological clocks capture the imagination because of their tie to geophysical time, and tools are now in hand to analyse their function in health and disease at the cellular and molecular level.

Potential biochemical pathways for the relationship between sleep duration and mortality

OBJECTIVE

The objective of this study was to elucidate new evidence on the presence of a relationship among sleep duration, cardiovascular mortality and total mortality, and to investigate sleep duration-related multiple biochemical changes.

METHODS

The longitudinal study is based on the SAKUCESS study of 12,489 residents of Japan aged 20-79 years at baseline.

RESULTS

In the study, compared to respondents who reported 7h of sleep, long sleep duration (≥9h) was associated with an increased risk of cardiovascular disease mortality and total mortality in men, hazard ratios (HRs) were 1.70 (95% confidence interval [CI]=1.07-2.70) and 2.73 (95% CI=1.22-6.11) and an increased risk of total mortality in women, HR was 1.85 (95% CI=1.09-3.13). Sleep duration was significantly associated with changes in blood biochemical levels. The results of the logistic regression analysis showed that the levels of multiple biochemical parameters are associated with increased risk of total mortality.

CONCLUSIONS

This is the first large longitudinal study to indicate that sleep duration was associated with changes in multiple biochemical levels in the blood and total mortality.

Subjective sleep complaints are associated with insulin resistance in individuals without diabetes: the PPP-Botnia Study

OBJECTIVE

Sleep disorders and subjective sleep complaints have been associated with increased risk of type 2 diabetes. The evidence with respect to insulin resistance (IR) and insulin secretion in individuals without type 2 diabetes has been scarce and elusive. We examined if subjective sleep complaints and their co-occurrence were associated with IR and insulin secretion in adult women and men without diabetes.

RESEARCH DESIGN AND METHODS

Women (n = 442) and men (n = 354) 18-75 years of age without type 2 diabetes underwent an oral glucose tolerance test (OGTT), with insulin and glucose measured at fasting and at 30 and 120 min. Complaints related to sleep apnea, insomnia, and daytime sleepiness were self-rated with the Basic Nordic Sleep Questionnaire.

RESULTS

In comparison with individuals with no or minor sleep complaints, those with more frequent complaints of sleep apnea, insomnia, and daytime sleepiness were more insulin resistant, as evidenced by higher fasting insulin concentrations and insulin and glucose responses to OGTT, and more frequently had high homeostasis model assessment of IR and low insulin sensitivity index values. The likelihood of being insulin resistant increased significantly and linearly according to the accumulation of co-occurring sleep complaints. These associations changed only a little when adjusted for mediating and confounding factors and for depressive symptoms. Sleep complaints were not associated with indices of deficiency in insulin secretion.

CONCLUSIONS

Subjective sleep complaints were associated with IR. The likelihood of being insulin resistant increased according to accumulation of co-occurring sleep complaints. Sleep complaints were not associated with deficiency in insulin secretion.

Sleep disturbances as nontraditional risk factors for development and progression of CKD: review of the evidence

Despite the high prevalence and enormous public health implications of chronic kidney disease (CKD), the factors responsible for its development and progression are incompletely understood. To date, only a few studies have attempted to objectively characterize sleep in patients with CKD prior to kidney failure, but emerging evidence suggests a high prevalence of sleep disorders, particularly obstructive sleep apnea. Laboratory and epidemiologic studies have shown that insufficient sleep and poor sleep quality promote the development and exacerbate the severity of 3 important risk factors for CKD, namely hypertension, type 2 diabetes, and obesity. In addition, sleep disturbances might have a direct effect on CKD through chronobiological alterations in the renin-angiotensin-aldosterone system and sympathetic nervous system activation. The negative impact of sleep disorders on vascular compliance and endothelial function also may have a deleterious effect on CKD. Sleep disturbances therefore may represent a novel risk factor for the development and progression of CKD. Optimizing sleep duration and quality and treating sleep disorders may reduce the severity and delay the progression of CKD.

Sleep duration and disorders in pregnancy: implications for glucose metabolism and pregnancy outcomes

Humans have an innate requirement for sleep that is intrinsically governed by circadian and endocrine systems. More recently, reduced sleep duration has gained significant attention for its possible contribution to metabolic dysfunction. Significant evidence suggests that reduced sleep duration may elevate the risk for impaired glucose functioning, insulin resistance and type 2 diabetes. However, to date, few studies have determined the implications of reduced sleep duration with regard to glucose control during pregnancy. With the high prevalence of overweight and obesity in women of reproductive age, the occurrence of gestational diabetes mellitus (GDM) is increasing. GDM results in elevated risk of maternal and fetal complications, as well as increased risk of type 2 diabetes postpartum. Infants born to women with GDM also carry a life-long risk of obesity and type 2 diabetes. The impact of reduced sleep on glucose management during pregnancy has not yet been fully assessed and a paucity of literature currently exits. Herein, we review the association between reduced sleep and impaired carbohydrate metabolism and propose how reduced sleep during pregnancy may result in further dysfunction of the carbohydrate axis. A particular focus will be given to sleep-disordered breathing, as well as GDM-complicated pregnancies. Putative mechanisms of action by which reduced sleep may adversely affect maternal and infant outcomes are also discussed. Finally, we will outline important research questions that need to be addressed.

Sleep duration and sleep quality are associated differently with alterations of glucose homeostasis

AIMS

Studies suggest that inadequate sleep duration and poor sleep quality increase the risk of impaired glucose regulation and diabetes. However, associations with specific markers of glucose homeostasis are less well explained. The objective of this study was to explore possible associations of sleep duration and sleep quality with markers of glucose homeostasis and glucose tolerance status in a healthy population-based study sample.

METHODS

The study comprised 771 participants from the Danish, population-based cross-sectional 'Health2008' study. Sleep duration and sleep quality were measured by self-report. Markers of glucose homeostasis were derived from a 3-point oral glucose tolerance test and included fasting plasma glucose, 2-h plasma glucose, HbA(1c), two measures of insulin sensitivity (the insulin sensitivity index(0,120) and homeostasis model assessment of insulin sensitivity), the homeostasis model assessment of β-cell function and glucose tolerance status. Associations of sleep duration and sleep quality with markers of glucose homeostasis and tolerance were analysed by multiple linear and logistic regression.

RESULTS

A 1-h increment in sleep duration was associated with a 0.3 mmol/mol (0.3%) decrement in HbA(1c) and a 25% reduction in the risk of having impaired glucose regulation. Further, a 1-point increment in sleep quality was associated with a 2% increase in both the insulin sensitivity index(0,120) and homeostasis model assessment of insulin sensitivity, as well as a 1% decrease in homeostasis model assessment of β-cell function.

CONCLUSIONS

In the present study, shorter sleep duration was mainly associated with later alterations in glucose homeostasis, whereas poorer sleep quality was mainly associated with earlier alterations in glucose homeostasis. Thus, adopting healthy sleep habits may benefit glucose metabolism in healthy populations.

Monounsaturated fatty acids prevent the aversive effects of obesity on locomotion, brain activity, and sleep behavior

Fat and physical inactivity are the most evident factors in the pathogenesis of obesity, and fat quality seems to play a crucial role for measures of glucose homeostasis. However, the impact of dietary fat quality on brain function, behavior, and sleep is basically unknown. In this study, mice were fed a diet supplemented with either monounsaturated fatty acids (MUFAs) or saturated fatty acids (SFAs) and their impact on glucose homeostasis, locomotion, brain activity, and sleep behavior was evaluated. MUFAs and SFAs led to a significant increase in fat mass but only feeding of SFAs was accompanied by glucose intolerance in mice. Radiotelemetry revealed a significant decrease in cortical activity in SFA-mice whereas MUFAs even improved activity. SFAs decreased wakefulness and increased non-rapid eye movement sleep. An intracerebroventricular application of insulin promoted locomotor activity in MUFA-fed mice, whereas SFA-mice were resistant. In humans, SFA-enriched diet led to a decrease in hippocampal and cortical activity determined by functional magnetic resonance imaging techniques. Together, dietary intake of MUFAs promoted insulin action in the brain with its beneficial effects for cortical activity, locomotion, and sleep, whereas a comparable intake of SFAs acted as a negative modulator of brain activity in mice and humans.

Effects of sleep restriction on glucose control and insulin secretion during diet-induced weight loss

Insufficient sleep is associated with changes in glucose tolerance, insulin secretion, and insulin action. Despite widespread use of weight-loss diets for metabolic risk reduction, the effects of insufficient sleep on glucose regulation in overweight dieters are not known. To examine the consequences of recurrent sleep restriction on 24-h blood glucose control during diet-induced weight loss, 10 overweight and obese adults (3F/7M; mean (s.d.) age 41 (5) years; BMI 27.4 (2.0) kg/m(2)) completed two 14-day treatments with hypocaloric diet and 8.5- or 5.5-h nighttime sleep opportunity in random order 7 (3) months apart. Oral and intravenous glucose tolerance test (IVGTT) data, fasting lipids and free fatty acids (FFA), 24-h blood glucose, insulin, C-peptide, and counter-regulatory hormone measurements were collected after each treatment. Participants had comparable weight loss (1.0 (0.3) BMI units) during each treatment. Bedtime restriction reduced sleep by 131 (30) min/day. Recurrent sleep curtailment decreased 24-h serum insulin concentrations (i.e., enhanced 24-h insulin economy) without changes in oral glucose tolerance and 24-h glucose control. This was accompanied by a decline in fasting blood glucose, increased fasting FFA, which suppressed normally following glucose ingestion, and lower total and low-density lipoprotein cholesterol concentrations. Sleep-loss-related changes in counter-regulatory hormone secretion during the IVGTT limited the utility of the test in this study. In conclusion, sleep restriction enhanced 24-h insulin economy without compromising glucose homeostasis in overweight individuals placed on a balanced hypocaloric diet. The changes in fasting blood glucose, insulin, lipid and FFA concentrations in sleep-restricted dieters resembled the pattern of human metabolic adaptation to reduced carbohydrate availability.

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.

Does Menopause Increase Diabetes Risk? Strategies for Diabetes Prevention in Midlife Women

Menopause is a significant milestone for midlife women. The characteristic changes in sex hormones and associated symptoms mark a time of increased risk for chronic disease, most notably cardiovascular disease. The diabetes epidemic, combined with recent epidemiologic studies linking sex hormone profiles with incident diabetes risk, have recently raised the possibility that the menopause may increase diabetes risk as well. This report reviews studies of menopause and diabetes risk, as well as the potential mechanisms through which menopause might affect traditional and more novel diabetes risk factors. Diabetes risk appears to be more strongly linked with factors associated with chronological aging and sex hormones rather than changes in menopausal status per se. Strategies to reduce diabetes risk, namely lifestyle changes, hormone therapy and other pharmacologic interventions are also discussed vis à vis midlife women and menopause.

Does inadequate sleep play a role in vulnerability to obesity?

The prevalence of obesity is increasing rapidly worldwide, which is cause for concern because obesity increases the risk of cardiovascular disease and diabetes, reduces life expectancy, and impairs quality of life. A better understanding of the risk factors for obesity is therefore a critical global health concern, and human biologists can play an important role in identifying these risk factors in various populations. The objective of this review is to present the evidence that inadequate sleep may be a novel risk factor associated with increased vulnerability to obesity and associated cardiometabolic disease. Experimental studies have found that short-term sleep restriction is associated with impaired glucose metabolism, dysregulation of appetite, and increased blood pressure. Observational studies have observed cross-sectional associations between short sleep duration (generally <6 h per night) and increased body mass index or obesity, prevalent diabetes, and prevalent hypertension. Some studies also reported an association between self-reported long sleep duration (generally >8 h per night) and cardiometabolic disease. A few prospective studies have found a significant increased risk of weight gain, incident diabetes, and incident hypertension associated with inadequate sleep. Given the potential link between inadequate sleep and obesity, a critical next step is to identify the social, cultural, and environmental determinants of sleep, which would help to identify vulnerable populations. Future human biology research should consider variation in sleep characteristics among different populations and determine whether the associations between sleep and obesity observed in Western populations persist elsewhere.

Electrocardiogram-based sleep spectrogram measures of sleep stability and glucose disposal in sleep disordered breathing

STUDY OBJECTIVES

Sleep disordered breathing (SDB) is independently associated with insulin resistance, glucose intolerance, and type 2 diabetes mellitus. Experimental sleep fragmentation has been shown to impair insulin sensitivity. Conventional electroencephalogram (EEG)-based sleep-quality measures have been inconsistently associated with indices of glucose metabolism. This analysis explored associations between glucose metabolism and an EEG-independent measure of sleep quality, the sleep spectrogram, which maps coupled oscillations of heart-rate variability and electrocardiogram (ECG)-derived respiration. The method allows improved characterization of the quality of stage 2 non-rapid eye movement (NREM) sleep.

DESIGN

Cross-sectional study.

SETTING

N/A.

PARTICIPANTS

Nondiabetic subjects with and without SDB (n = 118) underwent the frequently sampled intravenous glucose tolerance test (FSIVGTT) and a full-montage polysomnogram. The sleep spectrogram was generated from ECG collected during polysomnography.

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

Standard polysomnographic stages (stages 1, 2, 3+4, and rapid eye movement [REM]) were not associated with the disposition index (D(I)) derived from the FSIVGTT. In contrast, spectrographic high-frequency coupling (a marker of stable or "effective" sleep) duration was associated with increased, and very-low-frequency coupling (a marker of wake/REM/transitions) associated with reduced D(I). This relationship was noted after adjusting for age, sex, body mass index, slow wave sleep, total sleep time, stage 1, the arousal index, and the apnea-hypopnea index.

CONCLUSIONS

ECG-derived sleep-spectrogram measures of sleep quality are associated with alterations in glucose-insulin homeostasis. This alternate mode of estimating sleep quality could improve our understanding of sleep and sleep-breathing effects on glucose metabolism.

Associations of sleep disturbance and duration with metabolic risk factors in obese persons with type 2 diabetes: data from the Sleep AHEAD Study

PURPOSE

Some studies have found an association between sleep disturbances and metabolic risk, but none has examined this association in individuals with type 2 diabetes. The objective of this study was to determine the relationship between sleep disturbances and metabolic risk factors in obese patients with type 2 diabetes.

PATIENTS AND METHODS

This study was a cross-sectional examination of the relationship between sleep parameters (apnea/hypopnea index [AHI], time spent in various sleep stages) and metabolic risk markers (fasting glucose, hemoglobin A1c, lipids) using baseline data of the Sleep AHEAD cohort. Subjects (n = 305) were participants in Sleep AHEAD (Action for Health in Diabetes), a four-center ancillary study of the Look AHEAD study, a 16-center clinical trial of overweight and obese participants with type 2 diabetes, designed to assess the long-term effects of an intensive lifestyle intervention on cardiovascular events. All participants underwent one night of in-home polysomnography and provided a fasting blood sample. Regression analyses estimated the relationship between sleep variables and metabolic risk factors. Models were adjusted for study center, age, sex, race/ethnicity, waist circumference, smoking, alcohol intake, diabetes duration, and relevant medications.

RESULTS

Of 60 associations tested, only one was significant: fasting glucose was associated with sleep efficiency (estimate -0.53 ± [standard error] 0.26, P = 0.041). No associations were found between any of the sleep variables and lipid profile or hemoglobin A1c.

CONCLUSIONS

The present data show only weak associations between select sleep variables and metabolic risk factors and do not provide strong support for a role of sleep on metabolic abnormalities in obese patients with type 2 diabetes.

Loneliness is associated with sleep fragmentation in a communal society

STUDY OBJECTIVE

Loneliness has been shown to predict poor health. One hypothesized mechanism is that lonely individuals do not sleep as well as individuals who feel more connected to others. Our goal was to test whether loneliness is associated with sleep fragmentation or sleep duration.

DESIGN

Cross-sectional study.

SETTING

Members of a traditional, communal, agrarian society living in South Dakota.

PARTICIPANTS

Ninety-five participants (mean age 39.8 years, 55% female) who were ≥ 19 years of age at the study's inception.

INTERVENTIONS

Not applicable.

MEASUREMENTS AND RESULTS

We conducted interviews querying loneliness, depression, anxiety, and stress, as well as subjective sleep quality and daytime sleepiness. Study participants wore a wrist actigraph for one week to measure objective sleep properties; the two studied here were sleep fragmentation and sleep duration. Higher loneliness scores were associated with significantly higher levels of sleep fragmentation (β = 0.073, t = 2.55, P = 0.01), controlling for age, sex, body mass index, risk of sleep apnea, and negative affect (a factor comprising symptoms of depression and anxiety, and perceived stress). Loneliness was not associated with sleep duration or with either subjective sleep measure.

CONCLUSIONS

Loneliness was a significant predictor of sleep fragmentation. Humans' social nature may partly be manifest through our dependence on feeling secure in our social environment to sleep well.

Sleep architecture and glucose and insulin homeostasis in obese adolescents

OBJECTIVE

Sleep deprivation is associated with increased risk of adult type 2 diabetes mellitus (T2DM). It is uncertain whether sleep deprivation and/or altered sleep architecture affects glycemic regulation or insulin sensitivity or secretion. We hypothesized that in obese adolescents, sleep disturbances would associate with altered glucose and insulin homeostasis.

RESEARCH DESIGN AND METHODS

This cross-sectional observational study of 62 obese adolescents took place at the Clinical and Translational Research Center and Sleep Laboratory in a tertiary care children's hospital. Subjects underwent oral glucose tolerance test (OGTT), anthropometric measurements, overnight polysomnography, and frequently sampled intravenous glucose tolerance test (FSIGT). Hemoglobin A(1c) (HbA(1c)) and serial insulin and glucose levels were obtained, indices of insulin sensitivity and secretion were calculated, and sleep architecture was assessed. Correlation and regression analyses were performed to assess the association of total sleep and sleep stages with measures of insulin and glucose homeostasis, adjusted for confounding variables.

RESULTS

We found significant U-shaped (quadratic) associations between sleep duration and both HbA(1c) and serial glucose levels on OGTT and positive associations between slow-wave sleep (N3) duration and insulin secretory measures, independent of degree of obesity, pubertal stage, sex, and obstructive sleep apnea measures.

CONCLUSIONS

Insufficient and excessive sleep was associated with short-term and long-term hyperglycemia in our obese adolescents. Decreased N3 was associated with decreased insulin secretion. These effects may be related, with reduced insulin secretory capacity leading to hyperglycemia. We speculate that optimizing sleep may stave off the development of T2DM in obese adolescents.

Efficacy and safety of prolonged-release melatonin in insomnia patients with diabetes: a randomized, double-blind, crossover study

BACKGROUND

Diabetes is a major comorbidity in insomnia patients. The efficacy and safety of prolonged-release melatonin 2 mg in the treatment of glucose, lipid metabolism, and sleep was studied in 36 type 2 diabetic patients with insomnia (11 men, 25 women, age 46-77 years).

METHODS

In a randomized, double-blind, crossover study, the subjects were treated for 3 weeks (period 1) with prolonged-release melatonin or placebo, followed by a one-week washout period, and then crossed over for another 3 weeks (period 2) of treatment with the other preparation. All tablets were taken 2 hours before bedtime for a period of 3 weeks. In an extension period of 5 months, prolonged-release melatonin was given nightly to all patients in an open-label design. Sleep was objectively monitored in a subgroup of 22 patients using wrist actigraphy. Fasting glucose, fructosamine, insulin, C-peptide, triglycerides, total cholesterol, high-density and low-density lipoprotein cholesterol, and some antioxidants, as well as glycosylated hemoglobin (HbA1c) levels were measured at baseline and at the end of the study. All concomitant medications were continued throughout the study.

RESULTS

No significant changes in serum glucose, fructosamine, insulin, C-peptide, antioxidant levels or blood chemistry were observed after 3 weeks of prolonged-release melatonin treatment. Sleep efficiency, wake time after sleep onset, and number of awakenings improved significantly with prolonged-release melatonin as compared with placebo. Following 5 months of prolonged-release melatonin treatment, mean HbA1c (±standard deviation) was significantly lower than at baseline (9.13% ± 1.55% versus 8.47% ± 1.67%, respectively, P = 0.005).

CONCLUSION

Short-term use of prolonged-release melatonin improves sleep maintenance in type 2 diabetic patients with insomnia without affecting glucose and lipid metabolism. Long-term prolonged-release melatonin administration has a beneficial effect on HbA1c, suggesting improved glycemic control.