0969 INDUCING MORE SLEEP ON SCHOOL NIGHTS REDUCES SEDENTARY BEHAVIOR WITHOUT AFFECTING MORE VIGOROUS PHYSICAL ACTIVITY IN SHORT- SLEEPING ADOLESCENTS

Abstract

Nearly half of adolescents sleep less than 7 hours on school nights. Short sleep has been associated with obesity and we previously found that shortening sleep during summer months causes teens to eat more calories. However, there is concern that extending sleep may cut into physical activity time. Correlational findings are mixed on the relationship between sleep and physical activity during the school year, when short sleep is very common on school nights. Here we report results of a pilot study examining the impact of experimental sleep extension on the waking sedentary, light, and moderate/vigorous activity of habitually short-sleeping teens. Eighteen 14-17-year-olds who regularly slept 5–7 hours on school nights were enrolled in a 5-week protocol during the school year. Week 1 was a baseline to confirm habitual sleep. Participants then completed a pair of 2-week (weekday only) sleep conditions in a randomly counterbalanced order: Prescribed Habitual Sleep (HAB; school-night schedule matching baseline) and Sleep Extension (EXT; 1.5 hours longer in bed on school nights). Teens self-selected their weekend bedtimes. Teens wore wrist actigraphy to assess sleep fidelity and waist-mounted accelerometers to determine amounts of sedentary, light, moderate/vigorous activity during each condition. School night sleep averaged 6.16 hours during HAB and 7.34 hours during EXT (p<.001). Compared to HAB, during EXT teens averaged a 55 minute reduction in daily waking sedentary activity (p=.001) with a slight increase in light activity (7 minutes; p=.048) but no difference in moderate/vigorous activity (p=.53). Previous research indicates sedentary behavior is associated with obesity risk in teens. This pilot study indicates that, when short-sleeping teens sleep longer, they engage in less sedentary activity without seeming detriment in their moderate/vigorous activity. Further, other research suggests that risk for other negative consequences resulting from short sleep (i.e., higher caloric intake) may be attenuated. Cincinnati Children’s Research Foundation