br Conclusion br Conflicts of interest br Acknowledgments
Conflicts of interest
Acknowledgments This work was aided by the Japan Society for the Promotion of Science (JSPS) through the Grant-in-Aid for JSPS Fellows. The authors thank Dr. Thomas Maloney for kind and detailed editing of the manuscript.
Introduction Prevalence of obesity has reached epidemic proportions across all gender, age and ethnic groups. However, overweight and obesity in children is growing alarmingly. From 1990 to 2010 the global prevalence of childhood overweight and obesity increased from 4.2% to 6.7% and is expected to reach 9.1% in 2020 . Overweight and obese children are more likely to be obese adults, with many repercussions on health including cardiovascular disease, metabolic syndrome and cancer. Genetic factors, dietary behaviors, and physical activity are the main factors influencing overweight and obesity in young adolescent. However, other factors related with modernization of life have been related to obesity and need to be better addressed . Meta-analysis and systematic reviews have provided evidence that sleep patterns, sleep duration, and sleep quality are associated with overweight and obesity. Shorter sleepers had higher risk to be overweight/obese compared to longer ones, with a stronger association in boys than in girls [3–5]. Despite adolescents need about 9 to 10h of sleep , the National Sleep Foundation and a recent meta-analysis, reported that teens tend to have irregular sleep patterns across the week and only the 20% had an optimal sleep duration [7,8]. Short sleep duration may affect food intake, appetite, satiety and brain metabolism balance through the modification of hormonal responses [9,10]. Moreover, alterations in sleep patterns and sleep efficiency is often associated with unhealthy habits and lifestyle modifications, such as lower physical activities, consumption of high calories foods and beverages [11,12]. The aim of this study was to evaluate the association between sleeping habits, Mediterranean Diet pattern, and weight status using bioelectrical impedance analysis in an adolescent population.
Results The mean age of the adolescents was 12.0±0.7. Nearly 27% of participants were overweight and 24.5% were obese. Boys had a large proportion of overweight and obesity compared with girls (p<0.001). No other gender difference was found for the variables of interest. Moreover, adolescent Shine-Dalgarno sequence have parents with a higher education or a skilled profession were more likely to be under/normal weight. Physical activity was found to be lower in overweight and obese adolescent, while almost a half of the under/normal weight subject had a medium physical activities level. Only 84 adolescents (6%) had a good adherence to the Mediterranean Diet, with under/normal weight subject showing, on average, a greater adherence. The demographic characteristics of the 1586 adolescents (870 boys and 716 girls) distributed by BMI classification are showed in Table 1. Table 2 presents the sleep habits of the sample according to BMI category. The three groups shared similar bed times and wake times, with no significant differences. Under/normal weight adolescent had longer sleep time duration, both as total and weekdays sleep time, compared to the overweight and obese groups. Sleep duration was prolonged during weekends indifferently in all the three groups. When weekdays sleep time and weekend sleep time was compared within the three BMI category, a significant difference was found in all the groups, indicating a possible sleep deprivation pattern in all sample (p<0.001, data not shown). No difference in nap habits or length was found. The PDSS score increased among the three groups with a mean of 13.3±6.3 for under/normal weight, 9.8±5.9 for overweight and 14.7±6.7 for obese adolescent. Anthropometric characteristics and weight-related KIDMED score items by sleep timing behavior category are shown in Table 3. BMI, FM% and WC resulted significantly lower in EL category, while no association was found with KIDMED items or physical activities.