To assess the effects of early and late bedtimes and wake up
times on use of time and weight status in Australian school-aged
children. Observational cross-sectional study involving use of
time interviews and pedometers. Free-living Australian
adolescents. 2200 9- to 16-year-olds from all states of
Australia Measurements and Results: Bedtimes and wake times were
adjusted for age and sex and classified as early or late using
median splits. Adolescents were allocated into 4 sleep-wake
pattern groups: Early-bed/Early-rise; Early-bed/Late-rise; Late-
bed/Early-rise; Late-bed/Late-rise. The groups were compared for
use of time (screen time, physical activity, and study-related
time), sociodemographic characteristics, and weight status.
Adolescents in the Late-bed/Late-rise category experienced 48
min/d more screen time and 27 min less moderate-to-vigorous
physical activity (MVPA) (P < 0.0001) than adolescents in the
Early-bed/Early-rise category, in spite of similar sleep
durations. Late-bed/Late-rise adolescents h