Development of sleep-wake schedules during childhood and relationship with sleep duration.

OBJECTIVES: To present a longitudinal overview of the sleep schedules during weekdays and the weekend in a large sample of children and to examine the sleep-wake schedules in relation to nocturnal sleep duration and birth season.

DESIGN: Longitudinal survey design.

SETTING: Data were collected by home interviews and questionnaires.

PARTICIPANTS: Data for sleep schedules at the ages of 4, 5, and 6 years on weekdays were obtained for 1112 children. Data for bedtimes on the weekend were available for 1094 children, and data for wake times on the weekend were available for 1083 children.

OUTCOME MEASURES: Habitual bedtimes and wake times during weekdays and the weekend were reported by the mothers at the 3 ages. Nighttime sleep duration was calculated from bedtime to wake time. Birth characteristics came from medical records.

RESULTS: As children grow up, we found later bedtimes on the weekend for a given bedtime on weekdays. Interestingly, most children slept less during the weekend compared with weekdays. No significant difference (P > .10 for all) was found in the seasonal distribution of births in any of the sleep-wake schedules.

CONCLUSIONS: Despite a lack of a strong preference for sleep timing during childhood, the displacement of bedtime toward later hours during the weekend starts early in life. More important, sleep-wake patterns are associated with sleep duration and later bedtimes on the weekend seem to shorten sleep duration in most children.