Christina J. Calamaro

Shortened sleep duration does not predict obesity in adolescents

Obesity continues to be a major public health issue. In adolescents, there are limited studies on the relationship between obesity and sleep duration. We found hypothesized that an average sleep duration of <6u2003h in adolescents was associated with obesity. Data were from the National Longitudinal Study of Adolescent Health (ADD Health); a survey of 90u2003000 youths, aged 12–18u2003years; surveyed in several waves. The sample population for our study was 13u2003568. Weighted multiple logistic regression was used to identify the relationship between obesity at Wave II and sleep duration, having adjusted for skipping breakfastu2003≥u20032/week; race, gender, parental income, TVu2003≥u20032u2003h per day, depression, and obesity at Wave I. At Wave I, the mean age was 15.96u2003±u20030.11u2003years; mean sleep hours were 7.91u2003±u20030.04. At Waves I and II, respectively, 10.6 and 11.2% of adolescents were obese. Adjusted analyses suggest that the effect of shortened sleep duration in Wave I was not significantly predictive of obesity in Wave II (Pu2003<u20030.218). Longitudinally, depression and TVu2003≥u20032 u2003h per day at Wave I was associated with a higher risk of obesity at Wave II in adjusted analyses. Depressed adolescents were almost twice as likely to be obese (ORu2003=u20031.84, 95% CIu2003=u20031.25–2.72); adolescents who watched TVu2003≥u20032u2003h per day were 37% more likely to be obese (ORu2003=u20031.37, 95% CIu2003=u20031.09–1.72). Environmental factors including TVu2003≥u20032u2003h per day and depression were significantly associated with obesity; shortened sleep duration was not. Future longitudinal studies in adolescents are needed to determine whether timing of television watching directly influences sleep patterns and, ultimately, obesity.

Wired at a young age: the effect of caffeine and technology on sleep duration and body mass index in school-aged children

INTRODUCTIONnTwo problems affecting school-aged children in the United States are inadequate sleep and an increased prevalence of obesity. The purpose of this study was to quantify media-related technology use and caffeine consumption in order to assess their potential effects on sleep duration and body mass index (BMI) in children.nnnMETHODSnThe study was a secondary analysis of children 6 to 10 years of age (N = 625) from the National Sleep Foundations Sleep in America Poll. Regression analysis was used to assess the relationship between caffeine and technology use, sleep variables, and BMI, adjusting for age, race, gender, and general health.nnnRESULTSnAlmost 30% (29.5%) of the children consumed a daily caffeinated beverage, and 42.4% had a television in the bedroom. Children who drank caffeinated beverages had 15 fewer minutes of sleep per night than did children who did not drink such beverages (b = -0.27, p = .002). Children with three technology items in their bedroom received 45 fewer minutes of sleep than did children without these items in their bedroom (b = -0.75, p = .010). Having adjusted for variables, only drinking caffeinated beverages was associated with a BMI z score.nnnDISCUSSIONnThe complex relationships between caffeine intake and the use of technology with shortened periods of sleep and increased BMI need further study. Future research should explore how these risk factors for shortened periods of sleep can be modified in this young population.