Journal of Public Health Advance Access published January 31, 2016 Journal of Public Health | pp. 1–1
Correspondence Sleep duration and adiposity in early adolescents
Conflict of interest: None declared. References 1 Jiang YR, Spruyt K, Chen WJ et al. Associations between parentreported sleep duration and adiposity in Chinese early adolescents. J Public Health (Oxf ) 2015;37:277– 85. 2 Meng LP, Liu AL, Hu X et al. Report on childhood obesity in China (10): association of sleep duration with obesity. Biomed Environ Sci 2012;25:133 – 40. 3 Arau´jo J, Severo M, Ramos E. Sleep duration and adiposity during adolescence. Pediatrics 2012;130:e1146 – 54. 4 Chen T, Wu Z, Shen Z et al. Sleep duration in Chinese adolescents: biological, environmental, and behavioral predictors. Sleep Med 2014;15:1345–53. 5 Must A, Parisi SM. Sedentary behavior and sleep: paradoxical effects in association with childhood obesity. Int J Obes (Lond) 2009;33(Suppl 1):S82–6. 6 Mukherjee S, Patel SR, Kales SN et al. An Official American Thoracic Society Statement: The Importance of Healthy Sleep. Recommendations and Future Priorities. Am J Respir Crit Care Med 2015;191:1450–8.
Tomoyuki Kawada Department of Hygiene and Public Health, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-Ku, Tokyo 113-8602, Japan Address Correspondence to Tomoyuki Kawada, E-mail: [email protected] doi:10.1093/pubmed/fdw002
# The Author 2016. Published by Oxford University Press on behalf of Faculty of Public Health. All rights reserved. For permissions, please e-mail: [email protected].
1
Downloaded from http://jpubhealth.oxfordjournals.org/ at Universitätsbibliothek Osnabrück on February 7, 2016
Sirs Jiang et al. 1 investigated the association between parentreported sleep duration and adiposity in early adolescence, aged 10–12 years old by a cross-sectional study. Body mass index (BMI), waist-height ratio and body fat percentage (BF%) were used as indices of adiposity, and sleep duration was categorized into four groups with cut-off values of 8.89, 9.46 and 10.05 h, respectively. The authors concluded that shortest and shorter sleep duration were positively associated with BMI and BF% only in girls. I have some concerns on their study. First, Meng et al. 2 explored the association between sleep duration and obesity among children aged 7 – 11 years in urban areas of China by a cross-sectional study. A 7-day recall method was used to assess the sleep duration. They reported that the sleep duration was negatively associated with BMI and waist circumference (WC) in both boys and girls after adjustment for confounders, and children who slept less than 9.0 h per night had a higher risk for overweight and obesity (OR ¼ 1.29, 95% CI: 1.01, 1.64) and abdominal obesity (OR ¼ 1.38, 95% CI: 1.04, 1.83) as compared with those who slept for 10.0 – 10.9 h. In this report, there was no sex difference on the association. Second, Arau´jo et al. 3 evaluated the causal association between sleep duration at 13 years old and adiposity at 17 years old, and sleep duration was estimated by self-reported bedtimes and wake-up times. They concluded that sleep duration was inversely associated with BMI and BF% only in boys, although the significant association disappeared after adjustment for adiposity at 13 years. In this report, the significance was observed in boys, and the level of adiposity at baseline contributed to the causal association between sleep duration and adiposity after 4 years. Third, Chen et al. 4 conducted a cross-sectional study in adolescents aged 11–20 years. They reported that the overweight/ obesity was significantly associated with sleep duration less than 8 h per day on weekends. In contrast, the significance disappeared in sleep duration on weekdays. Although there was a gender difference in the percent of sleep duration less than 8 in weekdays, the author used sex for the adjustment of multivariate analysis, and stratified analysis by sex was not conducted. But their study has an advantage of presenting the different
association between sleep duration and adiposity in weekdays and weekends. Finally, Must et al. 5 reviewed the past reports and they speculated that a significant association between short sleep duration and weight gain was caused by direct metabolic effects of eating as well as indirect behavioral pathways including the presence of electronic media in children’s bedrooms. Relating to sleep duration in early adolescents, Mukherjee et al. 6 reported that age-based recommendations for sleep duration should be developed for children or adolescents by gathering more information of sleep duration on health effects. Anyway, insufficient sleep duration in adolescents should be checked in relation to adiposity and other metabolic components for preventive medicine.
Correspondence Sleep duration and adiposity in early adolescents
Conflict of interest: None declared. References 1 Jiang YR, Spruyt K, Chen WJ et al. Associations between parentreported sleep duration and adiposity in Chinese early adolescents. J Public Health (Oxf ) 2015;37:277– 85. 2 Meng LP, Liu AL, Hu X et al. Report on childhood obesity in China (10): association of sleep duration with obesity. Biomed Environ Sci 2012;25:133 – 40. 3 Arau´jo J, Severo M, Ramos E. Sleep duration and adiposity during adolescence. Pediatrics 2012;130:e1146 – 54. 4 Chen T, Wu Z, Shen Z et al. Sleep duration in Chinese adolescents: biological, environmental, and behavioral predictors. Sleep Med 2014;15:1345–53. 5 Must A, Parisi SM. Sedentary behavior and sleep: paradoxical effects in association with childhood obesity. Int J Obes (Lond) 2009;33(Suppl 1):S82–6. 6 Mukherjee S, Patel SR, Kales SN et al. An Official American Thoracic Society Statement: The Importance of Healthy Sleep. Recommendations and Future Priorities. Am J Respir Crit Care Med 2015;191:1450–8.
Tomoyuki Kawada Department of Hygiene and Public Health, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-Ku, Tokyo 113-8602, Japan Address Correspondence to Tomoyuki Kawada, E-mail: [email protected] doi:10.1093/pubmed/fdw002
# The Author 2016. Published by Oxford University Press on behalf of Faculty of Public Health. All rights reserved. For permissions, please e-mail: [email protected].
1
Downloaded from http://jpubhealth.oxfordjournals.org/ at Universitätsbibliothek Osnabrück on February 7, 2016
Sirs Jiang et al. 1 investigated the association between parentreported sleep duration and adiposity in early adolescence, aged 10–12 years old by a cross-sectional study. Body mass index (BMI), waist-height ratio and body fat percentage (BF%) were used as indices of adiposity, and sleep duration was categorized into four groups with cut-off values of 8.89, 9.46 and 10.05 h, respectively. The authors concluded that shortest and shorter sleep duration were positively associated with BMI and BF% only in girls. I have some concerns on their study. First, Meng et al. 2 explored the association between sleep duration and obesity among children aged 7 – 11 years in urban areas of China by a cross-sectional study. A 7-day recall method was used to assess the sleep duration. They reported that the sleep duration was negatively associated with BMI and waist circumference (WC) in both boys and girls after adjustment for confounders, and children who slept less than 9.0 h per night had a higher risk for overweight and obesity (OR ¼ 1.29, 95% CI: 1.01, 1.64) and abdominal obesity (OR ¼ 1.38, 95% CI: 1.04, 1.83) as compared with those who slept for 10.0 – 10.9 h. In this report, there was no sex difference on the association. Second, Arau´jo et al. 3 evaluated the causal association between sleep duration at 13 years old and adiposity at 17 years old, and sleep duration was estimated by self-reported bedtimes and wake-up times. They concluded that sleep duration was inversely associated with BMI and BF% only in boys, although the significant association disappeared after adjustment for adiposity at 13 years. In this report, the significance was observed in boys, and the level of adiposity at baseline contributed to the causal association between sleep duration and adiposity after 4 years. Third, Chen et al. 4 conducted a cross-sectional study in adolescents aged 11–20 years. They reported that the overweight/ obesity was significantly associated with sleep duration less than 8 h per day on weekends. In contrast, the significance disappeared in sleep duration on weekdays. Although there was a gender difference in the percent of sleep duration less than 8 in weekdays, the author used sex for the adjustment of multivariate analysis, and stratified analysis by sex was not conducted. But their study has an advantage of presenting the different
association between sleep duration and adiposity in weekdays and weekends. Finally, Must et al. 5 reviewed the past reports and they speculated that a significant association between short sleep duration and weight gain was caused by direct metabolic effects of eating as well as indirect behavioral pathways including the presence of electronic media in children’s bedrooms. Relating to sleep duration in early adolescents, Mukherjee et al. 6 reported that age-based recommendations for sleep duration should be developed for children or adolescents by gathering more information of sleep duration on health effects. Anyway, insufficient sleep duration in adolescents should be checked in relation to adiposity and other metabolic components for preventive medicine.
