Young late-nighters are less physically active and fit than their early-bird counterparts, suggests new research from Australia.
"Late bedtimes and late wake up times are associated with an unfavorable activity and weight status profile, independent of age, sex, household income, geographical remoteness, and sleep duration,” reads the abstract of the study, which was published in the journal SLEEP on Oct. 1.
A team of scientists from Adelaide studied a total of 2,200 Australian adolescents, aged 9 to 16 years old, using time interviews and pedometers.
Despite similar sleep durations, late-rising and -sleeping adolescents were observed to undertake 27 minutes less daily physical activity than the early-risers and -sleepers, who respectively went to bed and woke up 70 to 90 minutes and 60 to 80 minutes earlier.
"The children who went to bed late and woke up late, and the children who went to bed early and woke up early got virtually the same amount of sleep in total," advised study co-author Carol Maher from the University of South Australia in a press release.
"Scientists have realized in recent years that children who get less sleep tend to do worse on a variety of health outcomes, including the risk of being overweight and obese. Our study suggests that the timing of sleep is even more important."
Compared to earlier-risers, late-nighters spent 48 minutes longer per day watching television or playing video games, usually at night, had higher Body Mass Index scores, and were 1.47 times more likely to be overweight or obese.
“It is widely accepted that the sleep patterns of adolescents are fundamentally different from children and adults, and that it is normal for adolescents to stay up very late and sleep in late in the morning,” Maher said.
“Our findings show that this sleeping pattern is associated with unfavorable activity patterns and health outcomes, and that the adolescents who don’t follow this sleep pattern do better.”
Interestingly, late-risers tended to live in major cities with lower household incomes, fewer siblings, and a part-time job.