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

This study aimed to investigate the association between self‐reported sleep duration and general and abdominal obesity in Korean adults. A total of 8,717 adults aged 20–65 years from the Korean National Health and Nutrition Examination Survey (KNHANES) 2001 and 2005 were included. General obesity was defined as BMI ≥25 kg/m² and abdominal obesity as waist circumference ≥90 cm in men and ≥85 cm in women. To control for sociodemographic and lifestyle factors and comorbidities, multivariable logistic regression was used to calculate the adjusted odds ratios (ORs) and 95% confidence intervals (CIs) of general and abdominal obesity across the following sleep duration categories: ≤5, 6, 7, 8, and ≥9 h/day. Mean sleep duration (±s.d.) was 6.9 ± 1.3 h. Those sleeping ≤5 h/day had the highest BMI and waist circumference compared with those sleeping 7, 8, or ≥9 h/day (P < 0.05 for all comparisons). After controlling for sociodemographic and lifestyle factors, the adjusted ORs (95% CIs) associated with sleeping ≤5 h/day (vs. 7 h/day) were 1.25 (1.06–1.48) for general obesity and 1.24 (1.03–1.48) for abdominal obesity. Further adjustment for hypertension and diabetes mellitus did not significantly affect the associations. These data suggest that short sleep duration is significantly associated with a modest increase in general and abdominal obesity in Korean adults.     

Relationships between daytime sleepiness and sleep quality,duration, and phase among school-aged children: a cross-sectional survey

A cross-sectional survey was conducted to simultaneously evaluate sleep quality, duration, and phase in school-aged children and correlations between each dimension of sleep and daytime sleepiness were comprehensively examined. A cross-sectional survey was conducted with school-aged children enrolled in four public elementary schools in Joetsu city, Niigata prefecture in Japan (n = 1683). Among the collected responses (n = 1290), 1134 valid responses (547 boys and 587 girls) were analyzed (valid response rate was 87.90%). Data on daytime sleepiness, sleep quality (problems in sleeping at night), sleep duration (the average sleeping time during a week), and sleep phase (sleep timing: bedtime and rising time on weekdays, and sleep regularity: differences in bedtime and rising time between on weekdays and weekends) were collected. The results of multivariate logistic regression analysis indicated that the following dimensions were significantly correlated with daytime sleepiness: the decline in sleep quality [adjusted odds ratio (AOR) = 2.62, 95% confidence interval (CI) = 1.71–4.00], bedtime after 21:30 on weekdays (AOR = 1.58, 95% CI = 1.15–2.18), bedtime delay on weekends, compared to weekdays (AOR = 1.75, 95% CI = 1.27–2.41), and bedtime advance on weekends, compared to weekdays (AOR = 3.33, 95% CI = 1.78–6.20). Sleep dimensions that significantly affected daytime sleepiness in school-aged children are sleep quality, bedtime-timing, and regularity of bedtime. It is important to detect problems in night sleep and establish treatments, as well as to provide support for early bedding on weekdays and for a regular bedtime both on weekdays and on weekends to prevent daytime sleepiness in school-aged children.

     

The relationship between sleep and weight in a sample of adolescents

Research to date in young children and adults shows a strong, inverse relationship between sleep duration and risk for overweight and obesity. Fewer studies examining this relationship have been conducted in adolescents. The purpose of the article is to describe the relationship between sleep and weight in a population of adolescents, controlling for demographics, energy intake, energy expenditure, and depression. This is a cross-sectional study of 723 adolescents participating in population-based studies of the etiologic factors related to obesity. We examined the relationship between three weight-related dependent variables obtained through a clinical assessment and three sleep variables obtained through self-report. Average caloric intake from dietary recalls, average activity counts based on accelerometers, and depression were included as covariates and the analysis was stratified by gender and grade level. Our results show that the relationship between sleep duration and BMI is evident in middle-school boys (β = -0.32, s.e. = 0.06: P < 0.001) and girls (β = -0.18, s.e. = 0.08: P = 0.02) but largely absent in high-school students. Differences in sleep patterns have little association with weight in males, but in high-school girls, waking up late on weekends as compared to weekdays is associated with lower body fat (β = -0.80, s.e. = 0.40: P = 0.05) and a healthy weight status (β = -0.28, s.e. = 0.14: P = 0.05). This study adds to the evidence that, particularly for middle-school boys and girls, inadequate sleep is a risk factor for early adolescent obesity. Future research needs to examine the relationship longitudinally and to study potential mediators of the relationship.     

Short Sleep Duration and Childhood Obesity: Cross-Sectional Analysis in Peru and Patterns in Four Developing Countries

Background

We aimed to describe the patterns of nutritional status and sleep duration in children from Ethiopia, India, Peru and Vietnam; to assess the association between short sleep duration and overweight and obesity, and if this was similar among boys and girls in Peru.

Methods and Findings

Analysis of the Young Lives Study, younger cohort, third round. In Ethiopia there were 1,999 observations, 2,011, 2,052 and 2,000 in India, Peru and Vietnam, respectively. Analyses included participants with complete data for sleep duration, BMI, sex and age; missing data: 5.9% (Ethiopia), 4.1% (India), 6.0% (Peru) and 4.5% (Vietnam). Exposure was sleep duration per day: short (<10 hours) versus regular (10–11 hours). Outcome was overweight and obesity. Multivariable analyses were conducted using a hierarchical approach to assess the effect of variables at different levels. Overweight/obesity prevalence was 0.5%/0.2% (Ethiopia), 1.3%/0.3% (India), 6.1%/2.8% (Vietnam), and 15.8%/5.4% (Peru). Only Peruvian data was considered to explore the association between short sleep duration and overweight and obesity, with 1,929 children, aged 7.9±0.3 years, 50.3% boys. Short and regular sleep duration was 41.6% and 55.6%, respectively. Multivariable models showed that obesity was 64% more prevalent among children with short sleep duration, an estimate that lost significance after controlling for individual- and family-related variables (PR: 1.15; 95%CI: 0.81–1.64). Gender was an effect modifier of the association between short sleep duration and overweight (p = 0.030) but not obesity (p = 0.533): the prevalence ratio was greater than one across all the models for boys, yet it was less than one for girls.

Conclusions

Childhood overweight and obesity have different profiles across developing settings. In a sample of children living in resource-limited settings in Peru there is no association between short sleep duration and obesity; the crude association was slightly attenuated by children-related variables but strongly diminished by family-related variables.     

Correlations between sleep patterns and cardiovascular diseases in a Chinese middle-aged population

Epidemiological and animal studies have suggested an association between habitual sleep patterns and cardiovascular (CV) disease, but the results are still controversial. Therefore, the aims of this study are to investigate the relationships between habitual sleep patterns and CV disease based on Prospective Urban Rural Epidemiology (PURE) China study. PURE China study recruited 46 285 participants, aged 35–70, from 12 provinces and 115 communities in China. Habitual sleep patterns and CV disease were self-reported. Multilevel logistic regression was used in our analysis. In this study, 39 515 participants were eligible in our analysis, including 23 345 (59.1%) women and 16 170 (40.9%) men. Sleeping ≥9 h per day was associated with increased odds of CV disease (OR = 1.16, 95% CI: 1.01–1.32, p = 0.033) compared with sleeping 7–8 h per day. Taking daytime naps was also associated with an increased odds of CV disease, and the CV odds increased with increasing napping duration (p for trend < 0.001). For the sleeping < 6 h per day, we only found an association with coronary artery disease (CAD) (OR = 1.58, 95% CI: 1.01–2.48, p = 0.046). Participants with only 7–8 h sleep per night had lowest prevalence of CV disease (OR = 0.77, 95% CI: 0.65–0.90, p = 0.001) compared with other sleep patterns. Napping, long and short duration of habitual sleep may increase the odds of CV disease. Only participants sleeping 7–8 hours at night are recommended in this study, and large longitudinal studies are needed to confirm these results.     

Short sleep duration is associated with reduced leptin levels and increased adiposity: Results from the Quebec family study

Objective: To explore cross‐sectional associations between short sleep duration and variations in body fat indices and leptin levels during adulthood in a sample of men and women involved in the Québec Family Study. Research Methods and Procedures: Anthropometric measurements, plasma lipid‐lipoprotein profile, plasma leptin concentrations, and total sleep duration were determined in a sample of 323 men and 417 women ages 21 to 64 years. Results: When compared with adults reporting 7 to 8 hours of sleep per day, the adjusted odds ratio for overweight/obesity was 1.38 (95% confidence interval, 0.89 to 2.10) for those with 9 to 10 hours of sleep and 1.69 (95% confidence interval, 1.15 to 2.39) for those with 5 to 6 hours of sleep, after adjustment for age, sex, and physical activity level. In each sex, we observed lower adiposity indices in the 7‐ to 8‐hour sleeping group than in the 5‐ to 6‐hour sleeping group. However, all of these significant differences disappeared after statistical adjustment for plasma leptin levels. Finally, the well‐documented regression of plasma leptin levels over body fat mass was used to predict leptin levels of short‐duration sleepers (5 and 6 hours of sleep), which were then compared with their measured values. As expected, the measured leptin values were significantly lower than predicted values. Discussion: There may be optimal sleeping hours at which body weight regulation is facilitated. Indeed, short sleep duration predicts an increased risk of being overweight/obese in adults and is related to a reduced circulating leptin level relative to what is predicted by fat mass. Because sleep duration is a potentially modifiable risk factor, these findings might have important clinical implications for the prevention and treatment of obesity.     

Sleep Patterns of Day-Working,Evening High-Schooled Adolescents of São Paulo,Brazil

Children who grow up in developing countries of the world must work to help financially support their families, and they must also attend school. We investigated the impact of work on the sleep of working vs. nonworking high school students. Twenty-seven São Paulo, Brazil, public high school students (eight male and eight female working students plus six nonworking female and five nonworking male students) 14–18 yrs of age who attended school Monday–Friday between 19:00 to 22:30 h participated. A comprehensive questionnaire about work and living conditions, health status, and diseases and their symptoms was also answered. The activity level and rest pattern (sleep at night and napping during the day) were continuously assessed by wrist actigraphy (Ambulatory Monitoring, USA). The main variables were analyzed by a two-factor ANOVA with application of the Tukey HSD test for multiple comparisons, and the length of sleep during weekdays vs. weekends was compared by Student t-test. Working students went to sleep earlier weekends [F_(1,23) = 6.1; p = 0.02] and woke up earlier work days than nonworking students [F_(1,23) = 17.3; p = 0.001]. The length of nighttime sleep during weekdays was shorter among all the working [F_(1,23) = 16.7; p < 0.001] than all the nonworking students. The sleep duration of boys was shorter than of girls during weekends [F_(1,23) = 10.8; p < 0.001]. During weekdays, the duration of napping by working and nonworking male students was shorter than nonworking female students. During weekdays, working girls took the shortest naps [F_(1,23) = 5.6; p = 0.03]. The most commonly reported sleep complaint during weekdays was difficulty waking up in the morning [F_(1,23) = 6.5; p = 0.02]. During weekdays, the self-perceived sleep quality of working students was worse than nonworking students [F_(1,23) = 6.2; p = 0.02]. The findings of this study show that work has negative effects on the sleep of adolescents, with the possible build-up of a chronic sleep debt with potential consequent impact on quality of life and school learning.     

Outdoor artificial light at night,obesity, and sleep health: Cross-sectional analysis in the KoGES study

Obesity is a common disorder with many complications. Although chronodisruption plays a role in obesity, few epidemiological studies have investigated the association between artificial light at night (ALAN) and obesity. Since sleep health is related to both obesity and ALAN, we investigated the association between outdoor ALAN and obesity after adjusting for sleep health. We also investigated the association between outdoor ALAN and sleep health. This cross-sectional survey included 8526 adults, 39–70 years of age, who participated in the Korean Genome and Epidemiology Study. Outdoor ALAN data were obtained from satellite images provided by the US Defense Meteorological Satellite Program. We obtained individual data regarding outdoor ALAN; body mass index; depression; and sleep health including sleep duration, mid-sleep time, and insomnia; and other demographic data including age, sex, educational level, type of residential building, monthly household income, alcohol consumption, smoking status and consumption of caffeine or alcohol before sleep. A logistic regression model was used to investigate the association between outdoor ALAN and obesity. The prevalence of obesity differed significantly according to sex (women 47% versus men 39%, p < 0.001) and outdoor ALAN (high 55% versus low 40%, p < 0.001). Univariate logistic regression analysis revealed a significant association between high outdoor ALAN and obesity (odds ratio [OR] 1.24, 95% confidence interval [CI] 1.14–1.35, p < 0.001). Furthermore, multivariate logistic regression analyses showed that high outdoor ALAN was significantly associated with obesity after adjusting for age and sex (OR 1.25, 95% CI 1.14–1.37, p < 0.001) and even after controlling for various other confounding factors including age, sex, educational level, type of residential building, monthly household income, alcohol consumption, smoking, consumption of caffeine or alcohol before sleep, delayed sleep pattern, short sleep duration and habitual snoring (OR 1.20, 95% CI 1.06–1.36, p = 0.003). The findings of our study provide epidemiological evidence that outdoor ALAN is significantly related to obesity.     

Trends in the prevalence of overweight and obesity among young Australians, 1985, 1997, and 2004

Objective: To determine secular trends in overweight/obesity among 7‐ to 15‐year‐olds for the periods 1985, 1997, and 2004. Research Method and Procedures: Data from representative surveys conducted in New South Wales, Australia, in 1985, 1997, and 2004 were analyzed. Height and weight were measured, and BMI categories were created using International Obesity Task Force definitions. Students were grouped as Grades 2 + 4 + 6 and 8 + 10. Results: The prevalences of overweight/obesity for 1985, 1997, and 2004 were 10.9%, 20.6%, and 25.7% among the younger boys and 10.6%, 19.5%, and 26.1% among the older boys. The average annual rate of increase for 1985 to 1997 was 0.81% and for 1997 to 2004 was 0.73% among the younger boys and was 0.74% and 0.94% for the two periods among the older boys. The prevalences of overweight/obesity in 1985, 1997, and 2004 were 14.0%, 22.0%, and 24.8% among the younger girls and 8.3%, 17.9%, and 19.8% among the older girls, respectively. The average annual rates of increase for the two periods were 0.8% and 0.4% among the younger girls and 0.80% and 0.27% among the older girls. Change in the prevalence of overweight/obesity and socioeconomic status were not associated. Discussion: Over the period 1985 to 1997, the prevalence of overweight and obesity increased significantly among the younger and older boys and the younger girls. The prevalence of overweight, but not obesity, increased among the older girls over this period. Over the period 1997 to 2004, the prevalence of overweight/obesity combined increased significantly among boys of both age groups but not among girls.     

Does the Duration and Time of Sleep Increase the Risk of Allergic Rhinitis? Results of the 6-Year Nationwide Korea Youth Risk Behavior Web-Based Survey

Allergic rhinitis (AR) is the most common chronic disorder in the pediatric population. Although several studies have investigated the correlation between AR and sleep-related issues, the association between the duration and time of sleep and AR has not been analyzed in long-term national data. This study investigated the relationship between sleep time and duration and AR risk in middle- and high-school students (adolescents aged 12–18). We analyzed national data from the Korea Youth Risk Behavior Web-based Survey by the Korea Centers for Disease Control and Prevention from 2007–2012. The sample size was 274,480, with an average response rate of 96.2%. Multivariate logistic regression analyses were conducted to determine the relationship between sleep and AR risk. Furthermore, to determine the best-fitted model among independent variables such as sleep duration, sleep time, and the combination of sleep duration and sleep time, we used Akaike Information Criteria (AIC) to compare models. A total of 43,337 boys and 41,665 girls reported a diagnosis of AR at baseline. The odds ratio increased with age and with higher education and economic status of the parents. Further, students in mid-sized and large cities had stronger relationships to AR than those in small cities. In both genders, AR was associated with depression and suicidal ideation. In the analysis of sleep duration and sleep time, the odds ratio increased in both genders when sleep duration was <7 hours, and when the time of sleep was later than 24∶00 hours. Our results indicate an association between sleep time and duration and AR. This study is the first to focus on the relationship between sleep duration and time and AR in national survey data collected over 6 years.     

Eleven‐year Prevalence Trends of Obesity in Greek Children: First Evidence that Prevalence of Obesity Is Leveling Off

We examined 11‐year (1997–2007) trends in underweight, overweight, and obesity in Greek children. Population data derived from a yearly, school‐based health survey carried out between 1997 and 2007 in >80% of all Greek schools. Height and weight measurements from 651,582 children, aged 8–9 years (boys: 51.2%) were analyzed. The gender‐ and age‐specific BMI cutoff points by the International Obesity Task Force (IOTF) were used in order to define underweight, normal weight, overweight, and obesity. Trend analysis showed an increase in the prevalence of obesity from 7.2 ± 0.2% in 1997 to 11.3 ± 0.2% in 2004 for girls (P < 0.001) and from 8.1 ± 0.2% in 1997 to 12.3 ± 0.2% in 2004 for boys (P < 0.001). An apparent leveling off in obesity rates was observed during 2004–2007 for both boys and girls. The prevalence of overweight rose between 1997 and 2007 from 20.2 ± 0.2% to 26.7 ± 0.2% for girls (P < 0.001) and from 19.6 ± 0.2% to 26.5 ± 0.2% for boys (P < 0.001). The overall prevalence of thinness in the same period remained constant in both sexes. The presented population‐based data revealed that the prevalence of overweight and obesity among 8‐ to 9‐year‐old Greek children is alarmingly elevated, with the overweight rates rising continuously. However, an apparent leveling off in obesity rates for the past 4 consecutive years was documented for the first time in both genders.     

Social jet lag,chronotype and body mass index in 14–17-year-old adolescents

The relationship between sleep duration and obesity in adolescents is inconclusive. This may stem from a more complex relationship between sleep and obesity than previously considered. Shifts toward evening preferences, later sleep–wake times and irregular sleep–wake patterns are typical during adolescence but their relationship to body mass index (BMI) has been relatively unexplored. This cross-sectional study examined associations between sleep duration, midpoint of sleep and social jet lag (estimated from 7 days of continuous actigraphy monitoring), and morningness/eveningness with BMIs (BMI z-scores) and waist-to-height ratios in 14–17-year-old adolescents. Seventy participants were recruited from ninth and tenth grades at a public high school. Participants’ characteristics were as follows: 74% female, 75% post-pubertal, 36% Hispanic, 38% White, 22% Black, 4% Asian and 64% free/reduced lunch participants with a mean age of 15.5 (SD, 0.7). Forty-one percent of the participants were obese (BMI ≥ 95th percentile); 54% were abdominally obese (waist-to-height ratio ≥ 0.5). Multivariable general linear models were used to estimate the association between the independent variables (school night sleep duration, free night sleep duration, midpoint of sleep (corrected), social jet lag and morningness/eveningness) and the dependent variables (BMI z-scores and waist-to-height ratios). Social jet lag is positively associated with BMI z-scores (p < 0.01) and waist-to-height ratios (p = 0.01). Midpoint of sleep (corrected) is positively associated with waist-to-height ratios (p = 0.01). After adjusting for social jet lag, school night sleep duration was not associated with waist-to-height ratios or BMI z-scores. Morningness/eveningness did not moderate the association between sleep duration and BMI z-scores. Findings from this study suggest that chronobiological approaches to preventing and treating obesity may be important for accelerating progress in reducing obesity rates in adolescents.     

Prevalence of obesity in elementary schoolchildren living in Northeast Attica, Greece

Objective: To assess the prevalence of obesity and obesity trend in schoolchildren living in Northeast Attica, Greece. Research Methods and Procedures: Mean (standard deviation) and median weight and BMI were calculated in 4131 (2054 boys and 2077 girls) 6‐ to 11‐year‐old Greek schoolchildren living in Northeast Attica between November 2003 and April 2004. Two hundred thirty‐six (95 boys, 141 girls) immigrant children also participated in the study. The secular trend for obesity was determined comparing our data with those of a similar study performed in 1994. Results: Of boys, 27.8% were overweight, and 12.3% were obese. For girls, the corresponding values were 26.5% for overweight and 9.9% for obesity. There was an increase in the prevalence of overweight and obesity in the last 10 years in both sexes. For boys, overweight increased by 4.2% and obesity by 2.9%, whereas, for girls, overweight increased by 3.8% and obesity by 1.6%. Overweight and obesity were less prevalent in the immigrant children compared with their Greek peers. For immigrant boys, overweight was 15.9% and obesity was 7.9%, and for immigrant girls, overweight was 15.2% and obesity was 8.7%. Discussion: Greek schoolchildren living in Northeast Attica present a high prevalence of overweight and obesity and a positive secular change in the prevalence of obesity.     

The Relationship of Weight‐Related Attitudes With Suicidal Behaviors in Korean Adolescents

The objective of this study was to assess the relationship between weight‐related attitudes and suicidal behavior after consideration of depressive mood in Korean adolescents. The study population consisted of a nationally representative sample of 74,698 adolescents (n = 39,466 boys, 35,232 girls) in middle and high school who completed the Korea Youth Risk Behavior Web‐based Survey (KYRBWS) in 2007. Logistic regression models were used to examine the relationships between measures of weight‐related and self‐reported suicidal behavior, controlling for demographics, depressive mood, stress perception, level of school achievement, and substance use. Suicide attempts were surveyed among those reported to have suicidal ideation (n = 7,579 boys, 10,204 girls). Significantly more girls than boys reported suicidal ideation (29 vs. 19%) and suicide attempts (7.7 vs. 4.5%). Factors significantly associated with suicidal ideation were overestimation of weight (vs. correct estimation) and behaviors to lose or gain weight (vs. no weight control) among boys and overestimation of weight and attempting to lose weight among girls. In contrast, the odds of suicide attempts were significantly higher among boys who tried to lose, gain, or maintain their weight (vs. no weight control) and girls who underestimated their weight (vs. correct estimation) and tried to lose weight (vs. no weight control). Boys and girls classified as overweight or at risk for overweight were significantly less likely to report suicide attempts compared to those classified as underweight. Weight‐related attitudes, such as incorrect weight perception and weight control behaviors, seem to be useful indicators for identifying Korean adolescents who are at risk for suicidal behaviors.     

Chronotype and sleep duration are associated with stimulant consumption and BMI among Chinese undergraduates

The study sought to identify the association between stimulant consumption and social jetlag, chronotype as well as sleep duration among undergraduate students. A cross-sectional survey was conducted in the university town in Chongqing, China. Data were collected on 977 participants, age 20.06 (SD = 1.25) years old, using the Munich Chronotype Questionnaire (MCTQ) to measure social jetlag, chronotype and average sleep duration. A self-reported questionnaire was used to collect the information: BMI, demographic data, outdoor activity time, smoking status, alcohol consumption, coffee consumption and sugar-sweetened beverage consumption. The positive significant association was found between late chronotype and alcohol consumption (OR = 1.26, 95% CI [1.05–1.52]), being a current smoker (OR = 1.62, 95% CI [1.26–2.07]) and sugar-sweetened beverage consumption (OR = 1.42, 95% CI [1.17–1.72]). Average sleep duration was negatively associated with BMI (OR = 0.84, 95% CI [0.71–0.98]). Social jetlag did not find any association between stimulant consumption and BMI in the adjusted model. The results showed that Chinese undergraduate students had a negative significant association between average sleep duration and BMI, and late chronotype might affect the stimulant consumption among the group. This study may provide some implications for health management of obesity among undergraduate students in China.

     

Trends in Height and BMI of 6‐Year‐Old Children during the Nutrition Transition in Chile

Objective: We analyzed trends in height and BMI and their interaction in 6‐year‐old Chilean children over the last 15 years. Research Methods and Procedures: We calculated height for age z‐score (HAZ), BMI z‐score, prevalence of obesity, underweight, and stunting from cross‐sectional national school‐based annual population surveys in 1987, 1990, 1993, 1996, 2000, and 2002. Using mixed model analysis, we determined the risk of obesity according to height over time as odds ratios (ORs) and 95% confidence interval and the potential influence of height and year of study on BMI z‐score. Results: Over the study period, height increased by 2.8 cm in boys and 2.6 cm in girls, whereas stunting declined from 5% to 2% in both. Tallness increased by ～2%, BMI z‐score increased from +0.3 to +0.65 in boys and to +0.62 in girls, and HAZ increased from ?0.47 in boys and ?0.45 in girls to 0 in 2002. Underweight declined from 4% to 3%, whereas obesity rose from 5% to ～14%. The probability of obesity among tall children was significantly greater than that for normal height children (OR, 2.3 to 3.5). The lowest obesity risk was observed between ?2 and ?1 HAZ. The OR for obesity in the stunted relative to normal height children was variable, ranging from 1.23 to 0.65, whereas it was significant and consistently positive (1.1 to 1.7) for boys and girls when it was compared with the lowest obesity risk according to height. Discussion: Tallness is significantly associated with increased obesity risk in children, while stunting is also associated, but to a lesser degree.     

Sleep patterns of day-working, evening high-schooled adolescents of São Paulo, Brazil

Children who grow up in developing countries of the world must work to help financially support their families, and they must also attend school. We investigated the impact of work on the sleep of working vs. nonworking high school students. Twenty-seven S?o Paulo, Brazil, public high school students (eight male and eight female working students plus six nonworking female and five nonworking male students) 14-18 yrs of age who attended school Monday-Friday between 19:00 to 22:30h participated. A comprehensive questionnaire about work and living conditions, health status, and diseases and their symptoms was also answered. The activity level and rest pattern (sleep at night and napping during the day) were continuously assessed by wrist actigraphy (Ambulatory Monitoring, USA). The main variables were analyzed by a two-factor ANOVA with application of the Tukey HSD test for multiple comparisons, and the length of sleep during weekdays vs. weekends was compared by Student t-test. Working students went to sleep earlier weekends [F(1,23)=6.1; p=0.02] and woke up earlier work days than nonworking students [F(1,23) = 17.3; p = 0.001]. The length of nighttime sleep during weekdays was shorter among all the working [F(1,23)= 16.7; p <0.001] than all the nonworking students. The sleep duration of boys was shorter than of girls during weekends [F(1,23)= 10.8; p <0.001]. During weekdays, the duration of napping by working and nonworking male students was shorter than nonworking female students. During weekdays working girls took the shortest naps [F(1,23)= 5.6; p = 0.03]. The most commonly reported sleep complaint during weekdays was difficulty waking up in the morning [F(1,23) = 6.5; p = 0.02]. During weekdays, the self-perceived sleep quality of working students was worse than nonworking students [F(1,23) = 6.2; p = 0.02]. The findings of this study show that work has negative effects on the sleep of adolescents, with the possible build-up of a chronic sleep debt with potential consequent impact on quality of life and school learning.     

Effects of breastfeeding on trajectories of body fat and BMI throughout childhood

Objective: To investigate the effect of breastfeeding in healthy boys and girls on their trajectories of percent body fat (%BF) and BMI standard deviation scores (BMI–SDS) throughout childhood. Methods and Procedures: Analyses of the DOrtmund Nutritional and Anthropometric Longitudinally Designed (DONALD) Study included data from 219 male and 215 female term participants, born between 1984 and 1999, with repeated anthropometric measurements between 0.5 and 7 years and prospective data on duration of breastfeeding. Results: Among boys with an overweight mother (OW‐M), analyses adjusted for potential confounders revealed that not or shortly breastfed (≤17 weeks) boys did not experience the age‐dependent decrease in %BF seen in all children with normal weight mothers (NW‐Ms). In contrast, boys fully breastfed for >17 weeks were protected against the adverse effect of maternal overweight (effect of long breastfeeding vs. no/short breastfeeding among boys with OW‐Ms: 0.46%/year; s.e. 0.18; P = 0.01). There was also a suggestion of an interaction between maternal overweight and breastfeeding for the BMI–SDS trajectory (0.08 SDS/year; s.e. 0.04; P = 0.07). Among boys with NW‐Ms mothers and the corresponding subgroups of girls, breastfeeding had little effect on the development of %BF or BMI–SDS throughout childhood. Discussion: Our study suggests that breastfeeding could offset a potential programming effect for childhood adiposity among boys with OW‐Ms, to whom advice to breast‐feed should thus be specifically targeted.     

Racial/Ethnic and Gender Differences in Concern with Weight and in Bulimic Behaviors Among Adolescents

FIELD, ALISON E, GRAHAM A COLDITZ, KAREN E PETERSON. Racial/ethnic and gender differences in concern with weight and in bulimic behaviors among adolescents. This study examined cross-sectional gender and racial/ethnic differences in bulimic behaviors among adolescents. Subjects were 704 male and 621 female students at a large urban public high school in the Northeast. Approximately 61% of the girls and 43% of the boys reported trying to lose weight or maintain their current weight; 2.0% of the students reported using laxatives or vomiting to control their weight. The use of these behaviors to control weight was only slightly more common among girls than boys (2.7% vs. 1.4%,p=0.1). Although more black than white girls used laxatives or vomiting to control weight (odds ratio [OR]=11.9, 95% confidence interval [CI] 1.5–95.3), there were no racial/ethnic differences in these behaviors among boys. However, Hispanic boys were twice as likely as white boys to binge eat at least monthly (OR=2.0, 95% CI 1.1–3.6). Our results suggest that bulimic behaviors affect male and female adolescents from a variety of racial/ethnic backgrounds. In addition, in contrast to the large gender differences in the prevalence of dieting and binge eating, more modest differences were documented in the prevalence of using vomiting and laxatives to control weight.     

Racial Differences in the Tracking of Childhood BMI to Adulthood

Objective: The possibility that there are racial differences in the patterns of BMI (kilograms per meter squared) change throughout life has not been examined. For example, the high prevalence of obesity among black women could result from a higher prevalence of obesity among black girls or because normal‐weight black girls experience larger BMI increases in adolescence or adulthood than do their white counterparts. Therefore, we examined the tracking of childhood BMI into adulthood in a biracial (36% black) sample. Research Methods and Procedures: Five‐ to 14‐year‐old children (2392) were followed for (mean) 17 years. Childhood overweight was defined as BMI ≥ 95th percentile, and adult obesity was defined as BMI ≥ 30 kg/m². Results: The tracking of childhood BMI differed between whites and blacks. Among overweight children, 65% of white girls vs. 84% of black girls became obese adults, and predictive values among boys were 71% (whites) vs. 82% (blacks). These racial differences reflected contrasting patterns in the rate of BMI change. Although the initial BMI of black children was not higher than that of white children, BMI increases with age were larger among black girls and overweight black boys than among their white counterparts. In contrast, relatively thin (BMI < 50th percentile) white boys were more likely to become overweight adults than were their black counterparts. Discussion: These findings emphasize the black/white differences in BMI changes with age. Because of the adult health consequences of childhood‐onset obesity, early prevention should be given additional emphasis.