At a recent Pediatric Sleep Medicine meeting, I had a chance to talk to some researchers from  Australia about their studies of adolescents. I was very interested to compare some aspects of parental and school practices that differed between the two countries. They were quite surprised when I told them that extracurricular activities, particularly those involving sports practice and games, were occurring in the U.S. with greater frequency on school nights. When I asked about timing of those kinds of activities in their countries, they responded that they would almost always be ended “before tea-time”, which they defined as around 4:00 in the afternoon. 

They directed me to a study of theirs recently published in the journal Health Behavior and Education where they compared groups of teenagers from Australia and the United States on sleep duration, parent-set bedtimes, time spent in extracurricular activities, and school start time. This study is important because there have been very few direct comparisons across countries that look at specific cultural practices. The adolescents completed a sleep survey during a school class and also kept a sleep diary for 8 days. Australian teens were more likely to have a bedtime that was set by parents, by a considerable margin–17.5% Australia v. 6.8% U.S. The Australian teens also slept an average of 47 minutes more on school nights and had later school start times–8:32 am average for Australia v. 7:45 for the U.S. Finally, U.S. teens spent over an hour more each week participating in extracurricular activities than their Australian counterparts.

To find out how these factors related together, they performed regression analyses. Finding that sleep duration was shorter in older teens and for females, they controlled for these factors in subsequent analyses. The result was that school start time had the biggest influence on sleep duration. For every hour earlier school start time, students slept around half an hour less each night. Having a parent-set bedtime meant that teens slept almost half an hour more. Extracurricular activities had the smallest effect, with each hour of activities associated with only a few minutes less sleep.

These new results obviously relate to the debates about high school start times that are occurring in more and more places across the U.S. I was interested in the extracurricular activities because I have expressed concern in this blog about sports creeping into school nights later and later. Australian teens and U.S. teens spent on average about the same amount of time—roughly 2.5 hours per week playing sports. Of course the variability is high since some teens in both countries spend much more time than that weekly. But the Australian teens may be able to work in those hours “before tea-time” with less likely effect on curtailment of sleep.

Australia and the U.S. are different in many ways, but they are also similar in many respects. They are both relatively affluent as indicated by most measures such as the World Bank rankings. There are differences between the two countries in academic achievement as measured by the PISA rankings (, with Australia ranked considerably above the U.S. in Reading, Mathematics, and Science. It very well could be that the cultural factors related to sleep studied here have some relation to those differences.

Short, M.A., Gradisar, M., Lack, L., Wright, H.R., Dewald, J.F., Wolfson, A.R., & Carskadon, M.A. (20130). A Cross-Cultural Comparison of Sleep Duration Between U.S. and Australian Adolescents The Effect of School Start Time, Parent-Set Bedtimes, and Extracurricular Load. Health Education and Behavior, 40, 323-330.

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