0269 Restricting Sleep Increases Teens’ Sedentary Behavior Without Impacting Moderate to Vigorous Physical Activity

Abstract

Abstract Introduction Short sleep duration has been linked to obesity risk in adolescence. However, most research has focused on potential changes in appetite/intake, rather than physical activity or sedentary behaviors. It remains unknown if, in the daily lives of adolescents, sleep restriction increases moderate- to-vigorous physical activity (e.g., by providing more time for it) or discourages such activity (in favor of sedentary behaviors). This was the first study to use gold-standard objective measures to assess cause-and-effect relationships between sleep duration and the resulting activity levels of adolescents in the naturalistic environment. Methods N=104 healthy teens (ages 14–18) completed the 3-week within-subjects crossover sleep manipulation experiment during the summer. Following a 7-night a sleep stabilization week, teens were randomly assigned to 5 nights in Short Sleep (6.5hrs sleep opportunity) or Healthy Sleep (9.5hrs sleep opportunity). Following a 2-night “washout” period, they crossed over to the alternate sleep condition. Throughout the study, they wore validated waist-worn accelerometers to objectively measure sedentary and physical activity levels, and wrist-worn actigraphs to confirm adherence to their sleep condition. Results When in Short Sleep (vs. Healthy Sleep), teens on average slept 112 minutes less (p<.0001, d=1.72) per wrist actigraphy. Waist-worn accelerometers reflected 99 more minutes in sedentary behavior (p<.0001, d=.97), and 16 more minutes in light physical activity (p=.002, d=.31) during short sleep. Teens did not differ in moderate-to-vigorous physical activity between conditions (p=.95, d=.03). Conclusion Among healthy adolescents, a realistic dose of sleep restriction did not affect moderate-to-vigorous physical activity levels, but did sharply increase time in sedentary behavior. Given the negative weight and health consequences of sedentary behavior, these results have practical implications for obesity prevention/intervention efforts. They suggest that extending teen sleep may neither encourage nor discourage healthy physical activity, but may help curb unhealthy behaviors (e.g., sedentary behavior). Support R01 HL120879