Normative data on the sleep habits of Australian children and adolescents

Abstract

Study objective: To provide normative sleep data on 9-18 year old Australians.

Design: Cohort study.

Setting: Participants' homes.

Participants: 4032 Australians aged 9-18 years.

Interventions: N/A.

Measurements and results: Participants completed a 48h use of time recall, comprising sleep data for one complete night. Sleep duration, bedtime and wake time were compared across age groups, between genders, and between school and non-school days using ANOVA. Sleep duration declined with age (P < 0.0001) at the rate of 12 min/night per year of age on school days, and 4 min on non-school days. Girls slept slightly longer than boys (5 min/night; P = 0.03). Non-school day sleep was 16 min longer than school day sleep (P < 0.0001), with the difference increasing with age. Bedtimes got later with age (P < 0.0001), however there were no differences in bedtimes between boys and girls. Bedtimes occurred 34 min later on non-school days (P < 0.0001). Wake times were very similar across age groups on school days, but increased at the rate of 10 min/year of age on non-school days. Wake times were similar for boys and girls, and occurred on average 82 min later on non-school days (P < 0.0001). Overall, 17% of school days and 20% of non-school days failed to meet the American Centers for Disease Control and Prevention sleep duration guidelines.

Conclusions: Normative sleep data will provide a valuable yardstick for health and education professionals when dealing with sleep-related issues.

Figure 1

Box plots of sleep time for children and adolescents on school days (left panel) and non-school days (right panel). The white line at the center of the black box represents the median, and the upper and lower edges of the box the 75th and 25th percentiles. The ends of the whiskers represent the 90th and 10th percentiles. The dotted grey line represents the recommended sleep requirements according to the Centers for Disease Control and Prevention.

Figure 2

Comparison of school day sleeping times of young Australians from the current study (large dots, grey line) with recent data from other studies in developed countries. Note that in some cases, the number of data points for a country exceeds the number of studies conducted in that country because sleep duration data were presented separately for gender and/or region subsets. The dotted grey line represents the recommended sleep requirements according to the Centers for Disease Control and Prevention. A, Australia; B, Belgium; Br, Brazil; C, Canada^,; F, Finland^,; Fr, France; G, Germany; H, Hungary; N, Netherlands; No, Norway^,; S, Switzerland^,; Sp, Spain; Sw, Sweden; UK, United Kingdom^,,; US, United States.^,–

Figure 3

Comparison of non-school day sleeping times of young Australians from the current study (large dots, grey line) with recent data from other studies in developed countries. Note that in some cases, the number of data points for a country exceeds the number of studies conducted in that country because sleep duration data were presented separately for gender and/or region subsets. The dotted grey line represents the recommended sleep requirements according to the Centers for Disease Control and Prevention. A, Australia; C, Canada^,; F, Finland; Fr, France; G, Germany; No, Norway; S, Switzerland; UK, United Kingdom; US, United States.^,–