The association between sleep duration and general and abdominal obesity in Koreans: data from the Korean National Health and Nutrition Examination Survey, 2001 and 2005

Sleep Patterns, Eating Behavior and the Risk of Noncommunicable Diseases

Sleep is extremely important for the homeostasis of the organism. In recent years, various studies have been carried out to address factors related to sleep patterns and their influence on food choices, as well as on the onset of chronic noncommunicable diseases. The aim of this article is to provide a scientific literature review on the possible role of sleep patterns on eating behavior and the risk of noncommunicable diseases. A search was performed on Medline (PubMed interface) using several keywords (e.g., "Factors Influencing Sleep" OR "Sleep and Chronic Diseases"). Articles published between 2000 and the present date that relate sleep to cyclic metabolic processes and changes in eating behavior were selected. Changes in sleep patterns are increasingly detected today, and these modifications are mainly caused by work and lifestyle conditions as well as a growing dependence on electronic devices. Sleep deprivation and the resultant short sleep duration lead to an increased appetite via an increase in the hunger hormone (ghrelin) and a decrease in the satiety hormone (leptin). Nowadays, sleep is undervalued, and thus often impaired, with consequences for the performance of various body systems. Sleep deprivation alters physiological homeostasis and influences eating behavior as well as the onset of chronic diseases.

Investigation of spatial pattern of apnea disorder using geographic information system (GIS)-case study of Kermanshah metropolis

Background

Apnea disorder is influenced by social and environmental factors. By assessing its hot spots and geography, the foci of this disorder and its at-risk groups can be identified for health interventions. This study was conducted to investigate the spatial pattern of apnea disorder using GIS in the Kermanshah metropolis.

Methods

In cross-sectional study was conducted in kermanshah, the statistical population were 119 people (73.95% male and 26.05% female) of Kermanshah residents, which referred to the sleep center from 2012 to 2018 due to apnea disorder. Information was collected from the records of patients referred to the Sleep Disorder Center of Farabi Hospital, which is the only service center in the west part of Iran. The statistical tests were the mean center, standard distance, Getis-Ord Gi * index, nearest neighbor index, and kernel density estimation test in GIS software.

Results

The spatial pattern of patients with apnea disorder has cluster formation in the Kermanshah metropolis. The age group of 50-54 had more apnea disorder than other age groups. In this age group, women were more prone to apnea than men. In terms of education, people with high education are more affected by this disorder; So that with the increase in education level, apnea disorder had also increased. Also, the findings showed that the disorder was more common in unemployed, married, overweight people with BMI (25-30), and obese people (30-40).

Conclusion

The spatial pattern of patients with apnea disorder was clustered and does not correspond to the high population density centers located in the marginal and slum areas of the city. These can be used by stakeholders, including governmental organizations and health authorities at the national-regional level.

Assessment of sex differences in associations between sleep duration and lipid/glucose metabolism in urban Japan: a cross-sectional study

Inadequate sleep durations (short or long) are related to worsening of lipid/glucose metabolism, leading to atherosclerotic cardiovascular diseases (ASCVD). Few data exist on sex differences in this relationship that, to date, has been scarcely reported. This cross-sectional study included 6678 men and 4700 women at the Health Planning Center of Nihon University Hospital, located in the center of Tokyo, between September 2015 and October 2016. The prevalence of diabetes and dyslipidemia in the participants was 3.3% and 6.5%, respectively. Sleep duration was divided into five categories: < 5 h, 5-6 h, 6-7 h, 7-8 h, and ≥ 8 h. We examined the odds ratio (OR) and 95% confidence interval (CI) of lipid/glucose metabolism-related markers for the reference value defined in each guideline with 6-7 h as the reference of comparison. In men, a sleep duration of < 5 h was associated with ORs of 1.32 and 1.33 (95% CI, 1.01-1.73 and 1.02-1.74) for LDL-C level ≥ 120 mg/dL and non-HDL-C level of ≥ 150 mg/dL (defined as "borderline hyper" by the Japan Atherosclerosis Society Guidelines for Prevention of ASCVD 2017), respectively. Moreover, a sleep duration of < 5 h was associated with an OR of 1.77 (1.33-2.35) for fasting blood glucose of ≥ 100 mg/dL (defined as "high" by a specialized lifestyle checkup program in Japan). In women, sleep duration of < 5 h was associated with an OR of 1.70 (1.24-2.33) for HbA1c level of ≥ 5.6% (defined as "high" by a specialized life style checkup program in Japan). However, there was no association between sleep duration and serum lipid profile. Inadequate short sleep duration was as a potential risk factor of adverse lipid and/or glucose metabolism in both sexes. However, there were sex differences in associations between sleep duration and lipid/glucose metabolism in urban Japan. To further reduce risks of ASCVD, it is of particular importance to emphasize adequate sleep duration in both sexes.Trial registration UMIN ( http://www.umin.ac.jp/ ) Study ID: UMIN000037643 retrospectively registered on August 9, 2019.

Associations of Diet Quality and Sleep Quality with Obesity

Short sleep duration or poor sleep quality has been associated with an increased risk of obesity. Although the underlying mechanism remains unclear, one proposed pathway is poor diet quality. This cross-sectional study investigated whether diet quality modifies the association between sleep status and obesity in Korean adults. We used the baseline data and samples of 737 men and 428 women (n = 1165) aged 19–64, who participated in the prospective Ewha–Boramae cohort study. Sleep duration was dichotomized into ≥7 h (adequate) and <7 h (insufficient). Pittsburgh Sleep Quality Index (PSQI) values, reflecting sleep quality, were dichotomized into >5 (poor quality) and ≤5 (good quality). Diet quality was evaluated by the Recommended Food Score (RFS). Obesity was associated with higher rates of insufficient sleep and poor sleep quality in women, but not in men. After adjustment for covariates, women with poor sleep quality had a higher risk of obesity than women with good sleep quality (OR = 2.198; 95% CI = 1.027–4.704); this association occurred only in the group with RFS ≤ median score. Our findings support a significant association between sleep quality and obesity, and this association has been potentially modified by dietary quality in women.

Association between lifestyle habits and the prevalence of abdominal obesity after the Great East Japan Earthquake: The Fukushima Health Management Survey

BACKGROUND

The proportion of overweight individuals living in the evacuation zone of Fukushima increased after the Great East Japan Earthquake. However, the change in the prevalence of abdominal obesity has not been reported. Lifestyle habits and changes in these habits after the disaster might have affected the onset of abdominal obesity; however, the association between the two is unclear.

METHODS

This study evaluated 19,673 Japanese participants of the Fukushima Health Management Survey. We used data from general health check-ups conducted in 13 municipalities between 2008 and 2010. Follow-up examinations were performed from June 2011 to March 2013. Changes in the proportion of individuals with abdominal obesity before and after the disaster were compared. Then, lifestyle habits affecting these changes were assessed.

RESULTS

We found that 34.2% and 36.6% of participants (P < 0.001), both evacuees (37.0% and 42.1% (P < 0.001)) and non-evacuees (32.8% and 34.0% (P < 0.001)), had abdominal obesity before and after the disaster, respectively. Abdominal obesity was positively associated with smoking cessation, snacking after dinner and non-breakfast skipping after the disaster and alcohol drinking before and after the disaster (all P < 0.05). Smoking cessation was positively associated with abdominal obesity in both evacuees and non-evacuees and in both men and women (all P < 0.01).

CONCLUSIONS

The prevalence of abdominal obesity increased among residents in the area affected by nuclear disaster. It might be associated with not only lifestyle habits before the disaster but also changes in these habits after the disaster, especially smoking cessation.

Effects of poly-gamma-glutamic acid and vitamin B6 supplements on sleep status: a randomized intervention study

BACKGROUD/OBJECTIVES

Data regarding the effects of poly-γ-glutamic acid (γ-PGA) on sleep status are limited. This study aimed to test whether γ-PGA and vitamin B₆ (VitB6) supplements improve sleep duration and quality.

SUBJECTS/METHODS

A factorial randomized, double-blinded, placebo-controlled crossover study included 47 adults (25 men and 22 women) who were free of chronic disease. Stratified randomized allocation considered age and gender for three interventions, group A (supplementation with γ-PGA 600 mg; n = 16), group B (supplementation with VitB6 100 mg; n = 14), and group C (dual supplementation of both γ-PGA 600 mg and VitB6 100 mg; n = 17). Participants underwent a 1-mon intervention period, followed by a 1-mon washout period, and then a second 1-mon intervention period. Differences (mean ± SD) in nighttime sleep status before and after supplementation were compared between the placebo and intervention groups using nonparametric tests.

RESULTS

Significant changes in sleep duration (0.27 ± 0.98 h, P < 0.05) and the Pittsburgh Sleep Quality Index global score (−0.52 ± 1.58, P < 0.05) indicating improved sleep status were observed in the intervention compared with the placebo of group C while no significant changes were observed in groups A and B. No statistical significance was detected between the intervention and the placebo; however, there was a greater increase in the group C intervention (4.59 ± 38.5 ng/mL) in serum serotonin concentrations than the groups A and B interventions. No side effects were observed.

CONCLUSIONS

On the basis of these findings, the dual supplementation of γ-PGA and VitB6 may be effective as functional food components to improve nighttime sleep status.

Trial Registration

Clinical Research Information Service Identifier: KCT0005083

Sleep and cardiometabolic health in children and adults: examining sleep as a component of the 24-h day

STUDY OBJECTIVES

Sleep, physical activity and sedentary time are all known to play a role in cardiometabolic health. Compositional data analysis (CoDA) enables us to examine associations between 24-h use of time and health outcomes.

METHODS

Data were collected in the Child Health CheckPoint study, a one-off national population-cohort study conducted between February 2015 and March 2016. Wrist-worn actigraphy monitors (GENEActiv Original, Cambs, UK) were used to measure activity behaviours (sleep, physical activity and sedentary time) and sleep characteristics (sleep variability, midsleep, efficiency). CoDA was applied to determine the association between 24-h use of time and cardiometabolic risk markers (blood pressure; body mass index; apolipoprotein B/A1; glycoprotein acetyls; and composite metabolic syndrome score). Substitution modelling (one-for-remaining and one-for-one) examined the associations of reallocating sleep time with other activity behaviours.

RESULTS

Data were available for 1073 Australian children aged 11-12 years (50% male) and 1337 adults (13% male). Strong association was found between 24-h use of time and all cardiometabolic health outcomes. Longer sleep was associated with more favourable cardiovascular health. Sleep characteristics other than duration (efficiency, timing, variability) were weakly and inconsistently associated with outcomes. Reallocating time from sleep to moderate-vigorous physical activity (MVPA) had favourable associations with cardiometabolic health, but reallocating from sleep to sedentary time was associated with less favourable cardiometabolic health.

CONCLUSION

The 24-h activity composition is strongly associated with cardiometabolic health in children and adults. Days with more sleep and MVPA are associated with improved cardiometabolic health.

Breakfast Intake Effect on the Association between Fast-Food Consumption and the Risk of Obesity and Dyslipidemia in Korean Adults Aged 20-39 Years Based on the Korea National Health and Nutrition Examination Survey IV 2013-2014

We investigated the association between fast-food (FF) consumptions and the risk of overweight/obesity and dyslipidemia in Korean adults (20-39 years) based on the Korea National Health and Nutrition Examination Survey (2013-2014). We also examined the effect of breakfast intake on the risk of overweight/obesity and dyslipidemia according to their frequencies of FF consumption. FF consumption was categorized into 3 groups: < 1 time/month (n = 79); 1-3 times/month (n = 1,173); and ≥ 1 time/week (n = 474). People consuming FF ≥ 1 time/week had unhealthy lifestyles, higher intake of total calorie, fat, and protein, and higher levels of blood pressure, total cholesterol (TC) and low-density lipoprotein (LDL)-cholesterol than those consuming FF < 1 time/month. Logistic regression analysis showed higher risk of overweight/obesity in people consuming FF 1-3 times/month (odds ratio [OR], 2.525; confidence intervals [CIs], 1.169-5.452; p = 0.018) and ≥ 1 time/week (OR, 2.646; CIs, 1.128-6.208; p = 0.025) than those consuming FF < 1 time/month after the adjustment. The risk of dyslipidemia was also higher in people consuming FF ≥ 1 time/week than those consuming FF < 1 time/month after the adjustment (OR, 2.444; CIs, 1.047-5.704; p = 0.039). Furthermore, among people consuming FF ≥ 1 time/week, irregular breakfast consumers (≤ 2 times/week, n = 215) had significantly higher levels of triglyceride, TC, and LDL-C than regular breakfast consumers (5-6 times/week, n=180). Irregular breakfast consumers also showed a higher risk of dyslipidemia than regular breakfast consumers after the adjustment (OR, 2.913; CIs, 1.463-5.801; p = 0.002). In conclusion, frequent FF consumption increases the risk of obesity and dyslipidemia in Korean adults aged 20-39 years. Particularly among the frequent FF consumers, irregular breakfast intake may contribute to the increased risk of dyslipidemia. It may provide an evidence for proper dietary education to reduce the risk of overweight/obesity and dyslipidemia in Koreans adults aged 20-39 years.

Relationship between sleep and obesity among U.S. and South Korean college students

Background

Little is known about the relationship between sleep and obesity in young adults, particularly college students. This study examined the relationship between sleep (i.e., sleep duration and quality) and obesity in a large and diverse binational sample of college students.

Methods

Analyses were based on a 40-item paper survey from 2016/2017 to 2017/2018 academic years, with a 72% response rate. The samples were 1578 college students aged 18–25 years from five universities (two in the U.S. and three in South Korea). Weight and height were measured objectively; other measures (e.g., health behaviors) were self-reported. Multinomial logistic regression was used to assess the association between sleep duration and independent variables (race/nationality, gender, and BMI). Poisson regression was used to examine the relationship between sleep quality and independent variables.

Results

Overall, blacks had a higher adjusted odds ratio (AOR) of short sleep (< 7 h/night) than whites (AOR = 1.74, P < .01); overweight participants had a higher AOR of short sleep than normal weight participants (AOR = 1.52, P < .01); and obese participants had a higher AORs of both short and long sleep (> 9 h/night) (AOR = 1.67, P < .01; AOR = 1.79, P < .05, respectively). Among men, being black, overweight, and obesity were associated with short sleep (P < .05), whereas only obesity was related to short sleep among women (P < .05). In analyses stratified by race and nationality, overweight and obesity were related to short sleep among blacks only (P < .05). Overall, sleep quality (getting enough sleep to feel rested in the morning in the past 7 days) was worse in blacks and South Koreans than whites (P < .05), worse in women than men (P < .05), and worse in participants with obesity than normal weight participants (P < .05).

Conclusions

Obesity was associated with both short (< 7 h/night) and long sleep duration (> 9 h/night) and poor sleep quality among all participants. In comparison with whites, blacks were more like to have short sleep, and blacks and South Koreans had worse sleep quality. Further investigations using a larger sample of college students in multiple countries may be helpful to identify target populations who are at a greater risk of obesity and sleep problems.

Association between misalignment of circadian rhythm and obesity in Korean men: Sixth Korea National Health and Nutrition Examination Survey

Background: The disruption of circadian rhythm has been found to associate with obesity in vivo and in vitro. Sleep duration, eating habits, total feeding time, and nightshift work can also affect circadian rhythms. This study investigated the association between misalignment of circadian rhythm and obesity in Korean men, using a cross-sectional database.Methods: This study used data from the Korean National Health and Nutrition Examination Survey (KNHANES), whose study population was 3,658 men aged 18 to 60 years. General and abdominal obesity was defined as a body mass index (BMI) ≥ 25 kg/m² and waist circumference ≥ 90 cm, respectively. Circadian rhythm factors were determined with a self-report questionnaire and included breakfast frequency, sleep duration, and work time. Frequency of breakfast was divided into regular breakfast (five to seven times a week) and irregular breakfast (less than five times a week). Sleep duration was divided into less than 7 hours, 7-9 hours, and over 9 hours. Working time was defined as day/evening, night shift, and other type. The adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for general and abdominal obesity were calculated using multivariable logistic regression according to the number of factors that disturb the circadian rhythm.Results: Participants with 1 (aOR 1.34, 95% Cl 1.10-1.61) and ≥2 (aOR 1.62, 95% Cl 1.29-2.05) factors disturbing circadian rhythms were associated with elevated risk for general obesity. Similarly, those with 1 (aOR 1.33, 95% Cl 1.09-1.63) and ≥2 (aOR 1.70, 95% Cl 1.32-2.20) factors had elevated risk for abdominal obesity.Conclusions: Factors disturbing the circadian rhythm were associated with general and abdominal obesity. Additional studies are needed, and associations with metabolic diseases should be investigated.

Association Between Sleep and Obesity in African Americans in the Jackson Heart Study

BACKGROUND

In the United States, data from the National Health and Nutrition Examination Survey suggest that 68% of adults are overweight and obese. Obesity has been shown in previous cross-sectional and longitudinal studies to be influenced by short sleep duration, which can lead to unregulated appetite, excessive eating during awake time, and decreased energy expenditure.

OBJECTIVE

To examine the associations among sleep duration, sleep quality, body mass index (BMI), and waist circumference (WC) in African Americans.

METHODS

The sample included participants in the Jackson Heart Study. During a clinic visit, the sleep habits of participants were recorded via a sleep history questionnaire, and BMI and WC measurements were also recorded. Multivariate analysis was used to examine the associations among sleep duration, sleep quality, general obesity (measured by BMI), and abdominal obesity (measured by WC).

RESULTS

The authors studied participants who provided data for the variables of interest (N=3778; 1363 men and 2415 women). Of all participants, 3317 (87.8%) were overweight, and 2149 (56.9%) were obese. The mean (SD) BMI was 32.1 (7.2) kg/m2, and the mean (SD) WC was 103.3 (16.0) cm. Mean sleep duration was 6.3 (1.4) hours for men and 6.4 (1.5) hours for women. Among the men, a significant negative relationship was found between sleep duration and body composition: longer sleep was associated with lower BMI levels but negatively associated with WC in men (β=-1.06; P<.01)]. Sleep quality was positively associated with WC in men (β=1.20; P<.01) and women (β=0.61; P<.05).

CONCLUSIONS

This study's findings highlight the high rate of overweight and obesity among participants in the Jackson Heart Study. About one-fourth of the participants described themselves as enjoying ideal health. In men, longer sleep duration was associated with lower BMI levels and lower WC; in both men and women, good sleep quality was associated with lower WC. However, more research is needed to examine sleep and body composition as risk factors for disease development in African Americans.

Levels and correlates of 24-hour movement behaviors among South Koreans: Results from the Korea National Health and Nutrition Examination Surveys, 2014 and 2015

PURPOSE

This study aimed to examine the levels and correlates of 24-h movement behaviors (i.e., physical activity, sedentary time, and sleep), and different patterns of these behaviors in a nationally representative sample of South Koreans aged 12 years and older. This study also aimed to examine the sociodemographic correlates of 24-h movement behaviors stratified by age groups.

METHODS

Self-reported, repeated cross-sectional data from 10,708 participants in the 2014 and 2015 Korea National Health and Nutrition Examination surveys were used. Key variables included moderate-to-vigorous intensity physical activity, muscular strengthening exercises, walking, active transportation, sedentary time, and sleep. Sociodemographic variables included age, sex, household income, area of residence, and education level. Descriptive statistics by sex and age as well as general linear models by age group were performed.

RESULTS

The proportions of individuals meeting the moderate-to-vigorous intensity physical activity, muscular strengthening exercises, and sleep guidelines were, respectively, 21.6%, 22.1%, and 32.5% in male youth; 6.9%, 4.5%, and 22.8% in female youth; 55.5%, 30.8%, and 54.0% in male adults; 48.8%, 14.4%, and 57.6% in female adults; 44.0%, 30.6%, and 45.5% in male older adults; and 29.5%, 8.9%, and 37.3% in female older adults. The proportions of individuals showing the most ideal combinations of 24-h movement behaviors were only 3.2% in youth, 0.4% in adults, and 0 in older adults. Universally, older age, female sex, or living in metro Seoul were associated with unfavorable patterns of 24-h movement behaviors across different age groups. However, the associations of income and education with movement behaviors were mixed across age groups.

CONCLUSION

Overall, the proportion of South Koreans with a healthy 24-h movement behavior pattern is low. The sociodemographic correlates of different types of 24-h movement behaviors should be considered when designing targeted interventions for the promotion of healthy active living for South Koreans.

Association of Sleep Duration and Obesity According to Gender and Age in Korean Adults: Results from the Korea National Health and Nutrition Examination Survey 2007-2015

BACKGROUND

This study aimed to investigate associations between self-reported sleep duration and general and abdominal obesity in Korean adults stratified according to gender and age.

METHODS

Data from 41,805 adults, 18-110 years of age, collected by the Korea National Health and Nutrition Examination Survey (KNHANES) in 2007 and 2015, were analyzed. Multivariable logistic regression was used to calculate adjusted odds ratios (AORs) and 95% confidence intervals (CIs) for obesity and abdominal obesity by sleep duration after controlling for sociodemographic and lifestyle variables.

RESULTS

Among individuals 30-49 years of age, there was an increased AOR for obesity only for sleep duration ≤ 5 hour/day compared with sleep duration 6 to 8 hour/day, both in men (OR, 1.25; 95% CI, 1.02-1.54) and women (OR, 1.56; 95% CI, 1.29-1.90), after controlling for covariates. Regarding women, there was increased AOR for abdominal obesity for sleep duration ≤ 5 hour/day (OR, 1.45; 95% CI, 1.18-1.78) and ≥ 9 hour/day (OR, 1.38; 95% CI, 1.09-1.76) compared with sleep duration 6 to 8 hour/day. However, for elderly individuals (≥ 65 years), there was a negative association between sleep duration ≤ 5 hour/day and obesity, but not with abdominal obesity, in both men and women.

CONCLUSION

This study demonstrated a significant association between sleep duration and obesity, which varied according to gender and age.

Association between Sasang constitutional types with obesity factors and sleep quality

BACKGROUND

The purpose of this study was to investigate differences in obesity factors according to Sasang constitutional types and quality of sleep among Korean female college students.

METHODS

Surveys using Sasang-types questionnaires(QSCCⅡ) and quality of sleep questionnaires(PSQI; Pittsburgh Sleep Quality Index) were conducted with 339 Korean female college students. Additionally, obesity factors, including weight, fat mass, fat percent, abdominal fat percent, body mass index (BMI) and obesity rates were measured. All data analyses were performed using one-way ANOVA and two-way ANOVA.

RESULTS

The interaction between Sasang types and quality of sleep was presented in the quality of sleep status, subjective quality of sleep (domain 1), sleep duration (domain 3) and sleep disturbance (domain 5). Variables with interaction effects had significant differences in terms of obesity factors between groups with different quality of sleep according to the Sasang types. Moreover, significant differences in obesity factors between different Sasang types according to the quality of sleep were also observed.

CONCLUSION

This study characterized the reduction effect of improvement in quality of sleep on the fat mass of So-Yang type individuals and obesity factors in Tae-Eum type individuals. The results of this study will be used in improving sleep quality according to the Sasang types.

Association between Sleep Duration and Body Composition Measures in Korean Adults: The Korea National Health and Nutrition Examination Survey 2010

Background

The association between sleep duration and body composition measures in Korean adults remains unclear.

Methods

This cross-sectional study included 3,532 subjects aged ≥40 years (1,542 men and 1,990 women) who participated in the 2010 Korea National Health and Nutrition Examination Survey V-1. Self-reported sleep duration and anthropometric data were collected. Appendicular skeletal muscle mass (ASM) was quantified via dual-energy X-ray absorptiometry. Obesity was defined according to the body mass index and waist circumference. Sarcopenia was defined as the muscle mass percentage (ASM/weight) below the lowest quintile computed for the study population. Multivariate logistic regressions with or without adjustment for sociodemographic and lifestyle factors were used to evaluate the association of sleep duration with obesity and sarcopenia for participants who slept ≤5, 6–8, and ≥9 h/d. The results were expressed as odds ratios (ORs) with 95% confidence intervals (95% CIs).

Results

In women, the association between sleep duration and sarcopenia was stronger for individuals who slept ≥9 h/d than for those who slept 6–8 h/d (unadjusted OR, 1.99; 95% CI, 1.19–3.34; adjusted OR, 1.77; 95% CI, 1.06– 2.96).

Conclusion

Longer sleep duration is associated with a significantly higher incidence of sarcopenia in Korean women aged ≥40 years.

Effect of socio-economic status on sleep

AIM

Sufficient sleep is an important factor in physical and mental health. Sleep duration can be affected by socio-economic status (SES). This study aimed to examine the association between sleep duration and SES in Korean adolescents.

METHODS

This study was conducted with 1608 adolescents aged 12-18 years, based on data from the 2010 to 2012 Korean National Health and Nutrition Examination Survey (KNHANES). Sleep duration was self-reported in hours and three SES indicators were used: household income, basic livelihood security programmes and type of health insurance. Confounding factors in this study were age, mental health and physical activity.

RESULTS

Participants' average age was 15.6 ± 0.05 years and average sleep duration was 7.04 ± 0.05 h. There was a strong association between sleep duration and household income (P < 0.05) rather than other socio-economic indicators. In addition, it showed that sleep duration was significantly associated with age, body mass index (P < 0.05) and low mood is associated with short sleep and long sleep (>9 h/night). We found similar results in both genders, that is, that the highest income group had shorter sleep duration than the lowest income group.

CONCLUSIONS

This study shows that the SES, particularly household income, is an important factor in short sleep duration in Korean adolescents. Our findings suggest that, in future investigations of the adolescent's sleep problem, attention should be paid to household income.

Sex and age differences in the associations between sleep behaviors and all-cause mortality in older adults: results from the National Health and Nutrition Examination Surveys

OBJECTIVE

Our aim was to examine sex- and age-specific relationships of sleep behaviors with all-cause mortality rates.

METHODS

A retrospective cohort study was conducted among 5288 adults (≥50 years) from the 2005-2008 National Health and Nutrition Examination Surveys who were followed-up for 54.9 ± 1.2 months. Sleep duration was categorized as < 7 h, 7-8 h and >8 h. Two sleep quality indices were generated through factor analyses. 'Help-seeking behavior for sleep problems' and 'diagnosis with sleep disorders' were defined as yes/no questions. Sociodemographic covariates-adjusted Cox regression models were applied to estimate hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

A positive relationship was observed between long sleep and all-cause mortality rate in the overall sample (HR = 1.90, 95% CI: 1.38, 2.60), among males (HR = 1.48, 95% CI: 1.05, 2.09), females (HR = 2.32, 95% CI: 1.48, 3.61) and elderly (≥65 years) people (HR = 1.80, 95% CI: 1.30, 2.50). 'Sleepiness/sleep disturbance' (Factor I) and all-cause mortality rate were positively associated among males (HR = 1.22, 95% CI: 1.03, 1.45), whereas 'poor sleep-related daytime dysfunction' (Factor II) and all-cause mortality (HR = 0.75, 95% CI: 0.62, 0.91) were negatively associated among elderly people.

CONCLUSIONS

Sex- and age-specific relationships were observed between all-cause mortality rate and specific sleep behaviors among older adults.

Sleep Duration, Sleep Quality, Body Mass Index, and Waist Circumference among Young Adults from 24 Low- and Middle-Income and Two High-Income Countries

Obesity and its comorbidities have emerged as a leading public health concern. The aim of this study was to explore the relationship between body mass index (BMI), waist circumference (WC) and sleep patterns, including duration and disturbances. A cross-sectional questionnaire survey and anthropometric measurements were conducted with undergraduate university students that were randomly recruited in 26 universities in 24 low- and middle-income and two high-income countries. The sample included 18,211 (42.1% male and 57.9% female, mean age 21.0 in male and 20.7 years in female students) undergraduate university students. The overall BMI was a mean of 22.5 kg/m² for men and 22.0 kg/m² for women, and the mean WC was 78.4 cm for men and 73.8 cm for women. More than 39% of the students reported short sleep duration (≤6 h/day) and over 30% reported moderate to extreme sleep problems. In a linear multivariable regression, adjusted for sociodemographic and lifestyle factors, short sleep duration was positively associated with BMI in both men and women, and was positively associated with WC among women but not among men. Sleep quality or problems among men were not associated with BMI, while among women mild sleep problems were inversely associated with BMI, and poor sleep quality or problems were positively associated with WC both among men and women. The study confirmed an association between short sleep duration and increased BMI and, among women, increased WC, and an association between poor sleep quality and increased WC but not BMI. Further, differences in the association between sleep characteristics and BMI and WC were found by region and country income.

Women Who Sleep More Have Reduced Risk of Peptic Ulcer Disease; Korean National Health and Nutrition Examination Survey (2008-2009)

Sleep is integral to life and sleep duration is important in sleep quality, physical, and psychological health. Disturbances in sleep duration have been associated with increased risk of metabolic disorders, hypertension, and overall mortality. Sleep disturbance has also been linked with various gastrointestinal disorders. However, the association between sleep and peptic ulcer disease (PUD) has not been evaluated. We investigated the association between sleep duration and PUD. Subjects were included from the fifth Korean National Health and Nutrition Examination Survey conducted from 2008-2009. Individuals with PUD were defined as those with a physician diagnosis of PUD. Daily sleep duration was established by asking participants the amount of time that they slept per day. Multiple logistic regression models were used to evaluate the association of PUD and sleep duration. This study included 14,290 participants (8,209 women). The prevalence of PUD was 5.7% and was higher in men (6.8%) than in women (4.9%). Women who slept ≥9 hours were significantly less likely to have PUD compared to women who slept 7 hours. In men, longer sleep duration (≥9 hours) had a tendency toward PUD prevention. Our results suggest that longer sleep duration may play a protective role for PUD development.

Sleep Duration and Obesity in Adults: What Are the Connections?

Collectively, cross-sectional and longitudinal studies on self-reported sleep duration and obesity do not show a clear pattern of association with some showing a negative linear relationship, some showing a U-shaped relationship, and some showing no relationship. Associations between sleep duration and obesity seem stronger in younger adults. Cross-sectional studies using objectively measured sleep duration (actigraphy or polysomnography (PSG)) also show this mixed pattern whereas all longitudinal studies to date using actigraphy or PSG have failed to show a relationship with obesity/weight gain. It is still too early and a too easy solution to suggest that changing the sleep duration will cure the obesity epidemic. Given novel results on emotional stress and poor sleep as mediating factors in the relationship between sleep duration and obesity, detection and management of these should become the target of future clinical efforts as well as future research.

The Association between Sleep Duration and Hypertension in Non-obese Premenopausal Women in Korea

BACKGROUND

Previous studies have revealed that sleep duration is linked to both obesity and hypertension. Here, we evaluated the association between sleep duration and hypertension in obese and non-obese premenopausal women using representative national survey data from the Korean population.

METHODS

A total of 4,748 subjects over 20 years of age from the Korean National Health and Nutrition Examination Survey from 2010 to 2012 were included. To control for risk factors, multivariable logistic regression was used to calculate the adjusted odds ratios and 95% confidence intervals of hypertension across the following sleep duration categories: <6, 6-8, and >8 h/d.

RESULTS

Among the participants, 367 subjects (7.7%) had hypertension. Their mean sleep duration was 7 hours. In the non-obese subjects, after controlling for potential confounding variables, the odds ratio for hypertension was 1.86 fold greater in those with a sleep duration of <6 hours (odds ratio, 1.79; 95% confidence interval, 1.05 to 3.03) as compared to those who slept for 6.8 hours. However, there was no association between sleep duration and the risk of hypertension in obese subjects. Long sleep duration (over 8 h/d) was not associated with hypertension in either the non-obese or the obese subjects in this study.

CONCLUSION

Short sleep duration (less than 6 h/d) may be a significant risk factor for hypertension in non-obese premenopausal women. However, there is no association between sleep duration and the risk of hypertension in obese women.

Excessive Sleep and Lack of Sleep Are Associated With Slips and Falls in the Adult Korean Population: A Population-Based Cross-Sectional Study

Few studies have evaluated the impacts of excessive sleep duration on falls. This study investigated the associations between sleep duration and falls among Korean adults in a wide range of age groups while adjusting for numerous confounding factors. Data collected from study participants ranging in age from 19 to 109 years old were analyzed from the 2013 Korean Community Health Survey (KCHS). Sleep duration was divided into 5 groups: ≤5, 6, 7, 8, and ≥9  hours per day. The relations between sleep duration and falls (≥1 time or ≥2 times per year) were analyzed using simple and multiple logistic regression analyses with complex sampling. Age, sex, days of vigorous or moderate physical activity, income, education, alcohol use, smoking, stress, obesity, hypertension, diabetes mellitus, hyperlipidemia, stroke, angina or myocardial infarction, arthritis, and asthma were controlled for as confounding factors. Associations between sleep duration and falls were analyzed in 19 to 40, 41 to 60, and 61+ year age groups. Furthermore, the relations between sleep duration and indoor versus outdoor falls were analyzed. Both ≤6 and ≥8  hours of sleep per day were significantly associated with an increased incidence of falls (≥1 time and ≥2 times per year) in the overall adult population (P < 0.001 in both instances). In a subgroup analysis, sleep durations of ≤5 and ≥9  hours were significantly associated with an increased incidence of falls (≥1 time a year) in each age group. Six hours of sleep was not significantly associated with falls (≥2 times per year) in the 61+ year age group, and 8 and 9  hours of sleep were not significantly associated with falls (≥2 times a year) in the 19 to 40 year age group. This study demonstrated that long as well as short sleep durations are associated with an increased incidence of falls. However, these relations were not evident in elderly populations with short sleep durations or in young adults with long sleep durations.

Development of the National Healthy Sleep Awareness Project Sleep Health Surveillance Questions

OBJECTIVES

For the first time ever, as emphasized by inclusion in the Healthy People 2020 goals, sleep health is an emphasis of national health aims. The National Healthy Sleep Awareness Project (NHSAP) was tasked to propose questions for inclusion in the next Behavioral Risk Factor Surveillance System (BRFSS), a survey that includes a number of questions that target behaviors thought to impact health, as a means to measure community sleep health. The total number of questions could not exceed five, and had to include an assessment of the risk for obstructive sleep apnea (OSA).

METHODS

An appointed workgroup met via teleconference and face-to-face venues to develop an inventory of published survey questions being used to identify sleep health, to develop a framework on which to analyze the strengths and weaknesses of current survey questions concerning sleep, and to develop recommendations for sleep health and disease surveillance questions going forward.

RESULTS

The recommendation was to focus on certain existing BRFSS questions pertaining to sleep duration, quality, satisfaction, daytime alertness, and to add to these other BRFSS existing questions to make a modified STOP-BANG questionnaire (minus the N for neck circumference) to assess for risk of OSA.

CONCLUSIONS

Sleep health is an important dimension of health that has previously received less attention in national health surveys. We believe that 5 questions recommended for the upcoming BRFSS question banks will assist as important measures of sleep health, and may help to evaluate the effectiveness of interventions to improve sleep health in our nation.

Association between sleep duration and obesity is modified by dietary macronutrients intake in Korean

BACKGROUND

Short sleep duration has been reported to be inversely associated with risk of obesity.

METHODS

The effects of sleep duration on obesity-related variables and the interaction of sleep duration and dietary macronutrients consumption on risk of obesity were analysed in 14,111 subjects aged 20-79 from the Korean National Health and Nutrition Examination Survey.

RESULTS

Sleep restriction to less than 7h per day resulted in higher body mass index, plasma triglyceride level, and obesity prevalence for women, but not for men. Protein intake was significantly lower in subjects with lower sleep duration for both men and women. The subjects with short sleep duration were significantly higher fat consumption for men, whereas carbohydrate consumption for women. Among subjects whose carbohydrate consumption was above the median, subjects with sleep duration of less than 7h per day increased their odds of being obese (OR=1.255, 95% CI: 1.073-1.476, P<0.001) compared to subjects with sleep duration more than 7h per day for women.

CONCLUSIONS

Our results showed that sleep duration positively correlated with protein consumption, but negatively correlated with carbohydrate consumption, which might lead to high risk of obesity for women. Also, our findings support a significant association between sleep duration and obesity-related variables and this association has been potentially modified by dietary macronutrients consumption in women subjects.

Geographic distribution of insufficient sleep across the United States: a county-level hotspot analysis

INTRODUCTION

Insufficient sleep is associated with cardiometabolic risk and neurocognitive impairment. Determinants of insufficient sleep include many social and environmental factors. Assessment of geographic hot/coldspots may uncover novel risk groups and/or targets for public health intervention. The aim of this study was to discern geographic patterns in the first data set to include county-level sleep data.

METHODS

The 2009 Behavioral Risk Factor Surveillance System was used. Insufficient sleep was assessed with a survey item and dichotomized. Data from n = 2231 counties were available. Tests for significant spatial concentrations of high/low levels of insufficient sleep (hotspots/coldspots) used the Getis-Ord G* statistic of local spatial concentration, chosen due to the nature of missing data.

RESULTS

Eighty-four counties were hotspots, with high levels of insufficient sleep (P < .01), and 45 were coldspots, with low insufficient sleep (P < .01). Hotspots were found in Alabama (1 county), Arkansas (1), Georgia (1), Illinois (1), Kentucky (25), Louisiana (1), Missouri (4), Ohio (7), Tennessee (12), Texas (9), Virginia (6), and West Virginia (16). Coldspots were found in Alabama (1 county), Georgia (2), Illinois (6), Iowa (6), Michigan (2), Minnesota (1), North Carolina (1), Texas (7), Virginia (12), and Wisconsin (6). Several contiguous hotspots and coldspots were evident. Notably, the 17 counties with the highest levels of insufficient sleep were found in a contiguous set at the intersection of Kentucky, Tennessee, Virginia, and West Virginia (all P < .0002).

CONCLUSIONS

Geographic distribution of insufficient sleep in the United States is uneven. Some areas (most notably parts of Appalachia) experience disproportionately high amounts of insufficient sleep and may be targets of intervention. Further investigation of determinants of geographic variability needs to be explored, which would enhance the utility of these data for development of public health campaigns.

Sleep Duration and Waist Circumference in Adults: A Meta-Analysis

BACKGROUND

Previous research has demonstrated a relation between insufficient sleep and overall obesity. Waist circumference (WC), a measure of central adiposity, has been demonstrated to improve prediction of health risk. However, recent research on the relation of insufficient sleep duration to WC in adults has yielded inconsistent findings.

OBJECTIVES

To assess the magnitude and the consistency of the relation of insufficient sleep and WC.

METHODS

A systematic search of Internet and research databases using Google Scholar, Medline, PubMed, and PsycINFO through July 2013 was conducted. All articles in English with adult human subjects that included measurements of WC and sleep duration were reviewed. A random effects meta-analysis and regression analyses were performed. Heterogeneity and publication bias were checked. Results are expressed as Pearson correlations (r; 95% confidence interval).

RESULTS

Of 1,376 articles, 30 met inclusion criteria and 21 studies (22 samples for a total of 56,259 participants) provided sufficient data for meta-analysis. Results showed a significant negative relation between sleep duration and WC (r = -0.10, P < 0.0001) with significant heterogeneity related to sleep comparison method. Potential moderators of the relation between sleep duration and WC were not significant. Funnel plots showed no indication of publication bias. In addition, a fail-safe N calculation indicated that 418 studies with null effects would be necessary to bring the overall mean effect size to a trivial value of r = -0.005.

CONCLUSIONS

Internationally, cross-sectional studies demonstrate a significant negative relation between sleep duration and waist circumference, indicating shorter sleep durations covary with central adiposity. Future research should include prospective studies.

Sleep duration and associated factors in a community sample of elderly individuals in Korea

BACKGROUND

This study estimates the duration of sleep and its relationships with clinical correlates in a community sample of elderly individuals in Korea.

METHODS

A total of 1924 individuals aged 65 and over were interviewed in Korea. Sleep durations were classified into five categories: 5.00 h or less, 6.00 h per day, 7.00 h per day, 8.00 h per day, and 9.00 h or more per day. Sleep disturbance was classified into four sleep complaints: difficulty initiating sleep, difficulty maintaining sleep, early-morning awakening, and non-restorative sleep. The Mini-Mental Status Examination, the Geriatric Depression Scale, and questionnaires about the presence of cardiovascular disease were employed.

RESULTS

The most frequent self-reported sleep duration was 7.00 h. The mean sleep duration was 6.46 h. Female subjects, subjects between the ages of 75 and 79, and subjects with current depression were associated with sleeping for 6.00 h or less or 9.00 h or more. Subjects who lived alone and those with cardiovascular disease were associated with sleeping for 5.00 h or less. Subjects aged 80 and over, formally educated subjects, current smokers, and subjects with cognitive dysfunction were associated with sleeping for 9.00 h or more. Sleep disturbances according to sleep duration has a U-shaped distribution. We found that all sleep disturbances were significantly related to sleep durations of 6.00 h or less compared to sleep durations of 7.00 h. We also found that non-restorative sleep was significantly related to sleep durations of 8.00 h or more compared to sleep durations of 7.00 h.

CONCLUSION

A relatively high prevalence of short or long sleep duration was identified. Various sociodemographic variables influenced sleep duration. Depression, cognitive dysfunction, and cardiovascular disease were associated with short or long sleep duration. Careful attention should be paid to the health of elderly individuals who are short or long sleepers.

Correlates of self-reported sleep duration in middle-aged and elderly Koreans: from the Health Examinees Study

Though various factors related to fluctuations in sleep duration have been identified, information remains limited regarding the correlates of short and long sleep duration among the Korean population. Thus, we investigated characteristics that could be associated with short and/or long sleep duration among middle-aged and elderly Koreans. A total of 84,094 subjects (27,717 men and 56,377 women) who participated in the Health Examinees Study were analyzed by using multinomial logistic regression models. To evaluate whether sociodemographic factors, lifestyle factors, psychological conditions, anthropometry results, and health conditions were associated with short and/or long sleep duration, odds ratios (ORs) and 95% confidence intervals (CIs) were estimated with sleep duration of 6-7 hours as the reference group, accounting for putative covariates. Regardless of sexual differences, we found that adverse behaviors and lifestyle factors including low educational attainment, unemployment, being unmarried, current smoking status, lack of exercise, having irregular meals, poor psychosocial well-being, frequent stress events, and poor self-rated health were significantly associated with abnormal sleep duration. Similarly, diabetes mellitus and depression showed positive associations with abnormal sleep duration in both men and women. Our findings suggest that low sociodemographic characteristics, adverse lifestyle factors, poor psychological conditions, and certain disease morbidities could be associated with abnormal sleep duration in middle-aged and elderly Koreans.

The influence of sex and age on the relationship between sleep duration and metabolic syndrome in Korean adults

AIMS

To investigate the influence of sex and age on the relationship between sleep duration and metabolic syndrome in a nationally representative population.

METHODS

We used data from the Korea National Health and Nutrition Examination Survey (2001-2010) and enrolled 24,511 participants aged 20-79 years. Sleep duration was categorized into five groups: ≤5, 6, 7 (referent), 8, and ≥9h/day. Age was categorized into three groups: younger (20-39y), middle-aged (40-59y), and older (60-79y). The association between sleep duration and metabolic syndrome was assessed in the total, separately in men and women, then in six groups based on sex and age.

RESULTS

The prevalence of metabolic syndrome by sleep category demonstrated a U-shaped pattern in the total population. However, after adjusting for age, education, occupation, exercise, smoking, alcohol, and body mass index, the prevalence of metabolic syndrome increased in long sleepers (OR 1.31; 95% CI 1.14-1.51) but not in short sleepers (OR 1.00; 95% CI 0.89-1.11). The relationship between sleep duration and metabolic syndrome varied by sex and age-long sleep (≥9h/day) was positively associated with metabolic syndrome only in younger (OR 2.13; 95% CI 1.38-3.28) and middle-aged (OR 1.63; 95% CI 1.21-2.21) women. Short sleep (≤5h/day) was not associated with metabolic syndrome in any sex and age groups. However, extremely short sleep (≤4h/day) was associated with metabolic syndrome in middle-aged men (OR 1.76, 95% CI 1.05-2.96).

CONCLUSION

These data suggest that sex and age significantly modify the relationship between sleep duration and metabolic syndrome.

Polysomnographically determined sleep and body mass index in patients with insomnia

We assessed associations between polysomnographically determined sleep, especially the amount of slow-wave sleep (SWS), and body mass index (BMI) in patients with insomnia. One hundred and forty-one insomniacs and 55 healthy volunteers completed overnight polysomnographic recordings, and we measured height and body weight. No significant correlations were obtained between total sleep time and BMI among insomniacs. Compared with normal volunteers, insomnia patients exhibited longer sleep latency and shorter total sleep duration. While the two groups had no significant differences in BMI, insomniacs presented with more N1 but less time spend in SWS and rapid eye movement sleep (REMS). Based on their SWS time, we divided insomnia patients into three groups: short (26.99±13.88), intermediate (59.24±8.12), and long (102.21±26.17) SWS groups. The short-SWS group had significantly greater BMI than the long-SWS group. Further analyses with multiple linear regression showed a significant negative correlation between the amount of SWS and BMI scores in insomniacs, whereas no such correlation was found in healthy volunteers after controlling for potential confounds (e.g., age, sex and AHI). Our study suggests that low amounts of SWS may be associated with higher BMI in patients with insomnia.

Sleep duration and glycemic control in patients with diabetes mellitus: Korea National Health and Nutrition Examination Survey 2007-2010

Short sleep duration has been reported to increase the risk of diabetes. However, the influence of sleep duration on glycemic control in diabetic patients has not been clarified. In this study we evaluated the association between sleep duration and glycemic control in diabetic patients. We analyzed the data from the Korea National Health and Nutrition Examination Survey (KNHANES) 2007-2010. Sleep duration was classified into five groups: <6, 6, 7, 8, and ≥9 h/day. Fasting blood glucose and HbA1c showed a U-shaped trend according to sleep duration. Sleep duration of 7 h/day had the lowest HbA1c (7.26%) among the subjects (P=0.026). In the older age group (≥65 yr), a sleep duration of 6 h/day was associated with the lowest HbA1c (7.26%). The adjusted odds ratio (OR) with a 95% confidence interval (CI) of worse glycemic control (HbA1c ≥7.0%) in group of sleep duration of ≥9 h/day was 1.48 (1.04-2.13) compared with the group of 7 h/day. This relationship disappeared after adjusting duration of diabetes (OR, 1.38; 95% CI, 0.93-2.03). Our results suggest that sleep duration and glycemic control in diabetic patients has U-shaped relationship which was mainly affected by duration of diabetes.

Sleep duration and all-cause mortality: a critical review of measurement and associations

PURPOSE

Variation in sleep duration has been linked with mortality risk. The purpose of this review is to provide an updated evaluation of the literature on sleep duration and mortality, including a critical examination of sleep duration measurement and an examination of correlates of self-reported sleep duration.

METHODS

We conducted a systematic search of studies reporting associations between sleep duration and all-cause mortality and extracted the sleep duration measure and the measure(s) of association.

RESULTS

We identified 42 prospective studies of sleep duration and mortality drawing on 35 distinct study populations worldwide. Unlike previous reviews, we find that the published literature does not support a consistent finding of an association between self-reported sleep duration and mortality. Most studies have employed survey measures of sleep duration, which are not highly correlated with estimates based on physiologic measures.

CONCLUSIONS

Despite a large body of literature, it is premature to conclude, as previous reviews have, that a robust, U-shaped association between sleep duration and mortality risk exists across populations. Careful attention must be paid to measurement, response bias, confounding, and reverse causation in the interpretation of associations between sleep duration and mortality.

Sleep duration and metabolic syndrome in adult populations: a meta-analysis of observational studies

OBJECTIVE

Epidemiological studies have repeatedly investigated the association between sleep duration and metabolic syndrome. However, the results have been inconsistent. This meta-analysis aimed to summarize the current evidence from cross-sectional and prospective cohort studies that evaluated this.

DATA SOURCES

Relevant studies were identified by systematically searching the PubMed, Cochrane CENTRAL, EMBASE and PsycINFO databases through November 2012 without language restriction.

STUDY SELECTION

We identified 12 cross-sectional studies with 76 027 participants including 14 404 cases of metabolic syndrome, and 3 cohort studies with 2055 participants and 283 incident cases of metabolic syndrome.

RESULTS

For short sleep durations (<5 to 6 h), the odds ratios (OR) was 1.27 (95% confidence interval (CI)=1.10-1.48, I(2)=75.5%) in the 12 cross-sectional studies and 1.62 (95% CI=0.74-3.55, I(2)=71.4%) in the 3 cohort studies; for long sleep durations (>8 to 10 h), the OR was 1.23 (95% CI=1.02-1.49, I(2)=75.8%) in the 11 cross-sectional studies and 1.62 (95% CI=0.86-3.04, I(2)=0.0%) in the 2 cohort studies.

CONCLUSIONS

Short and long sleep durations are risky behaviors for increasing the risk of metabolic syndrome and thus have important public health implications, as sleep habits are amenable to behavioral interventions. The available data are sparse, and further studies, especially longitudinal studies, are needed to facilitate a better understanding of these associations.

The role of sleep duration in the regulation of energy balance: effects on energy intakes and expenditure

Short sleep duration and obesity are common occurrence in today's society. An extensive literature from cross-sectional and longitudinal epidemiological studies shows a relationship between short sleep and prevalence of obesity and weight gain. However, causality cannot be inferred from such studies. Clinical intervention studies have examined whether reducing sleep in normal sleepers, typically sleeping 7-9 h/night, can affect energy intake, energy expenditure, and endocrine regulators of energy balance. The aim of this review is to evaluate studies that have assessed food intake, energy expenditure, and leptin and ghrelin levels after periods of restricted and normal sleep. Most studies support the notion that restricting sleep increases food intake, but the effects on energy expenditure are mixed. Differences in methodology and component of energy expenditure analyzed may account for the discrepancies. Studies examining the effects of sleep on leptin and ghrelin have provided conflicting results with increased, reduced, or unchanged leptin and ghrelin levels after restricted sleep compared to normal sleep. Energy balance of study participants and potential sex differences may account for the varied results. Studies should strive for constant energy balance and feeding schedules when assessing the role of sleep on hormonal profile. Although studies suggest that restricting sleep may lead to weight gain via increased food intake, research is needed to examine the impact on energy expenditure and endocrine controls. Also, studies have been of short duration, and there is little knowledge on the reverse question: does increasing sleep duration in short sleepers lead to negative energy balance?

Sleep duration and its correlates in middle-aged and elderly Chinese women: the Shanghai Women's Health Study

BACKGROUND

Abnormal sleep duration, either long or short, is associated with disease risk and mortality. Little information is available on sleep duration and its correlates among Chinese women.

METHODS

Using information collected from 68,832 women who participated in the Shanghai Women's Health Study (SWHS), we evaluated sleep duration and its correlations with sociodemographic and lifestyle factors, health status, and anthropometric measurements and their indexes using polynomial logistic regression.

RESULTS

The mean age of the study population was 59.6 years (SD=9.0; range: 44.6-79.9 years) at time of sleep duration assessment. Approximately 80% of women reported sleeping 6-8 h/day, 11.5% slept 5h or less, and 8.7% slept 9h or more. As expected, age was the strongest predictor for sleep duration and was negatively correlated with sleep duration. In general, sleep duration was positively associated with energy intake, intakes of total meat and fruits, body mass index (BMI), waist-hip ratio (WHR), and waist circumference (WC) after adjustment for age and other factors. Both short and long sleep duration were negatively associated with education level, family income, and leisure-time physical activity and positively associated with number of live births, history of night shift work, and certain chronic diseases, compared to sleep duration around 7 h/day (6.5-7.4h/day). Short sleep duration was related to tea consumption and passive smoking. Long sleep duration was related to menopausal status and marital status.

CONCLUSIONS

In this large, population-based study, we found that sleep duration among middle-aged and elderly Chinese women was associated with several sociodemographic and lifestyle factors and with disease status. The main limitation of the study is the cross-sectional design that does not allow us to draw any causal inference. However, this study provides information for future investigation into the nature of these associations so that recommendations can be developed to reduce sleep problems in middle-aged and elderly Chinese women. It also provides important information on potential confounders for investigation of sleep duration on health outcomes in this population.

State and regional prevalence of sleep disturbance and daytime fatigue

STUDY OBJECTIVES

Social and demographic influences are important for sleep attainment. Geographic location has not been previously explored.

METHODS

Data from the 2006 Behavioral Risk Factor Surveillance System (BRFSS) were used (N = 157,319). Participants answered a question on Sleep Disturbance and Daytime Fatigue. Thirty-six states/regions provided data on these items. Prevalence estimates were adjusted for age, sex, ethnoracial group, education, income, employment, general health, healthcare access, and depression. Chi-squared tests were conducted across states and census regions, and pseudo-R(2) values were computed for the effect of state, relative to other predictors. To evaluate potential mediators of census region differences, an analysis of p value change associated with specific covariates and covariate groups was undertaken.

RESULTS

Adjusted prevalence rates of Sleep Disturbance differed across states/regions overall (χ(2) = 412.3, p < 0.0001), as well as separately for men (χ(2) = 139.5, p < 0.0001) and women (χ(2) = 350.0, p < 0.0001), as did rates of Daytime Fatigue overall (χ(2) = 245.7, p < 0.0001), and separately for men (χ(2) = 117.5, p < 0.0001) and women (χ(2) = 181.2, p < 0.0001). Analysis of pseudo-R(2) values revealed that despite these significant findings, state differences were an overall weak predictor, representing 1.30% to 1.73% of the magnitude of the effect of the best predictor (mental health). When Census regions were compared, significant differences were found for Sleep Disturbance (p = 0.002), but after adjustment for covariates, these were no longer significant. Differences existed for Daytime Fatigue in adjusted analyses overall (p < 0.0001), with the West reporting the fewest complaints and the South reporting the most.

CONCLUSIONS

These results demonstrate that reports of sleep related complaints vary across states, independent (at least partially) of factors that influence circadian rhythms (e.g., latitude).

Short sleep and obesity in a large national cohort of Thai adults

OBJECTIVE

To investigate the relationship between short sleep and obesity among Thai adults.

DESIGN

Both 4-year longitudinal and cross-sectional analyses of a large national cohort.

SETTING

Thai adults residing nationwide from 2005 to 2009.

PARTICIPANTS

Cohort members were enrolled as distance learners at Sukhothai Thammathirat Open University (N=87 134 in 2005 and 60 569 at 2009 follow-up). At 2005 baseline, 95% were between 20 and 49 years of age.

MEASURES

Self-reported sleep duration was categorised as <6, 6, 7, 8 and ≥9 h. For all analyses (2005 and 2009 cross-sectional and 2005-2009 longitudinal), we used multinomial logistic regression models to assess the effect of sleep duration on abnormal body size (underweight, overweight-at-risk, obese). Results were adjusted for an array of relevant covariates.

RESULTS

At the last cohort follow-up in 2009, cross-sectional associations linked short sleep (<6 h) and obesity: adjusted ORs (AOR) =1.49, 95% CIs 1.32 to 1.68 for women and AOR=1.36, 95% CI 1.21 to 1.52 for men. The earlier cross-sectional baseline results in 2005 were quite similar. Longitudinal analysis (2005-2009) of 4-year incremental weight gain (5 to <10%, 10 to <20% and 20%+) strongly supported the short sleep-obesity relationship (significant AORs of 1.10, 1.30 and 1.69, respectively).

CONCLUSIONS

The results are internally consistent (2005 and 2009) and longitudinally confirmatory of a short sleep effect on obesity among Thai adults. Further research is needed to elucidate causal mechanisms underlying the sleep-obesity relationship.

Short sleep duration preferentially increases abdominal adiposity in adults: preliminary evidence

What is already known about this subject •  The evidence that short sleep duration is another determinant of obesity is accumulating. •  Lack of sleep has been reported to constitute a metabolic stressor, with increased cortisol concentrations as the end product. What this study adds •  This is the first study to show that short sleep duration is associated with a preferential increase in abdominal adiposity in adults.

SUMMARY

The aim of this 6-year longitudinal study was to verify whether short sleep duration preferentially increases abdominal adiposity in adults. A total of 276 adults, aged 18-64 years, from the Quebec Family Study were available for this study. Anthropometric measurements (body mass index and waist circumference), self-reported sleep duration and several covariates were assessed. A regression equation derived from the changes in body mass index and waist circumference of normal- and long-duration sleepers (reference category, ≥ 7 h of sleep per night, n = 233) was used to predict the change in waist circumference of short-duration sleepers (≤6 h of sleep per night, n = 43). Additionally, the influence of sleep duration on waist circumference changes was modelled by using linear regression in both sleep duration groups, adjusting for changes in body mass index and other covariates. We observed that measured (actual) changes in waist circumference were significantly greater than predicted changes (mean ± SEM: 3.41 ± 0.53 vs. 2.69 ± 0.51 cm, respectively, P < 0.05), implying that short-duration sleepers had an excess of abdominal fat accumulation over the 6-year follow-up period. After controlling for the changes in total adiposity as measured by body mass index, only short-duration sleepers gained more abdominal adiposity over 6 years. The present study provides evidence that short sleep duration is associated with preferential increases in abdominal adiposity in adults. This finding is of particular concern because abdominal adiposity is correlated with a number of metabolic anomalies.

The epidemiology of diabetes in Korea

Diabetes is an increasing global health problem worldwide. Diabetes and its complications have become a major cause of morbidity and mortality in Korea. The prevalence of diabetes in Korea has increased six- to seven-fold from 1.5% to 9.9% in the past 40 years. The prevalence of impaired fasting glucose also increased to about 20% in 2009. The International Diabetes Federation has estimated that the prevalence of diabetes will rise to 11.4% in 2030. Possible risk factors for diabetes in Korea are age, male gender, obesity, prediabetes, gestational diabetes, smoking, decreased physical activity, and short sleep duration. With increasing obesity, especially in childhood, and improved longevity, the prevalence of diabetes is expected to dramatically increase more than previously estimated. Therefore, public efforts to introduce healthy lifestyle changes and diabetic prevention programs are necessary to reduce the global epidemic of diabetes.

Metabolic, endocrine, and immune consequences of sleep deprivation

Over the last three to four decades, it has been observed that the average total hours of sleep have decreased to less than seven hours per person per night. Concomitantly, global figures relating to obesity and diabetes mellitus have increased in an alarming fashion in adults and children, and it has been hypothesized that neuro-hormonal changes accompanying this behavioral sleep deprivation may lead to insulin resistance and, subsequently, to diabetes mellitus. Sleep deprivation has been associated with multiple physiological changes, including increased cortisol and ghrelin levels, decreased leptin levels and impaired glucose metabolism. Experimental studies have also shown an increase in inflammatory and pro-inflammatory markers, which are indicators of body stress, under sleep deprivation. This review elaborates further on this hypothesis, exploring the molecular basis for the link between both entities and the underlying pathophysiology that results in insulin resistance and diabetes mellitus. We review the results of experimental and epidemiological studies, specifically examining the relationship between sleep duration and the immune and endocrine systems.

Relationships of sleep duration with sociodemographic and health-related factors, psychiatric disorders and sleep disturbances in a community sample of Korean adults

The aim of this study is to examine relationships of sleep duration with sociodemographic and health-related factors, psychiatric disorders and sleep disturbances in a nationwide sample in Korea. A total of 6510 subjects aged 18-64 years participated in this study. Logistic regression was used to calculate the odd ratios and 95% confidence intervals of the covariates, psychiatric disorders and sleep disturbances across the following sleep duration categories: 5 h or less, 6, 7, 8 and 9 h or more per day. Low levels of education, unemployment and physical illness were associated with sleeping for 5 h or less and 9 h or more. Being older and widowed/divorced/separated, high levels of physical activity, pain/discomfort, obesity and high scores on the General Health Questionnaires were associated with sleeping for 5 h or less. Female, being younger and underweight were associated with sleeping for 9 h or more. Alcohol dependence, anxiety disorder and social phobia were associated significantly with sleeping for 5 h or less and 9 h or more. Other psychiatric disorders were more common in subjects who slept for 5 h or less (e.g. alcohol use disorder, mood disorder, major depressive disorder, dysthymic disorder, obsessive-compulsive disorder and specific phobia) or 9 h or more (e.g. post-traumatic stress disorder). In addition, subjects who slept for 5 h or less reported more sleep disturbances than did subjects who slept for 7 h. Short or long sleep is associated with psychiatric disorders and/or sleep disturbance, therefore attention to the mental health of short or long sleepers is needed.