It seems that it is not how long or how much sleep a young person gets but rather when they go to bed that is important.

Children who go to bed early and get up early seem to be more active and spend less time as a whole in front of electronic media. This is the findings of a recent study, Sleep Duration or Bedtime? Exploring the Relationship between Sleep Habits and Weight Status and Activity Patterns, that was published in SLEEP.

Lead researcher, Carol Maher research fellow at the Australian Research Council, based at the University of South Australia, said “We don’t know if it’s their sleep patterns have knock-on effects to the kinds of activities they do or if their activities affect their sleep patterns.”

“All we can say is it’s clear from our study the kids who have that early to bed, early to wake up sleep pattern are doing better and are less likely to be overweight or obese.

“It kind of goes against some wisdom we have heard that teenagers’ sleep patterns are biologically different and it’s normal for them not to go to bed early and be waking up late.”

The researchers took 2,200 young people from states all across Australia and aged between 9 and 16 year olds. They were then divided into 4 groups:

  1. early to bed, early to wake
  2. early to bed, late to wake
  3. late to bed, early to wake; and
  4. late to bed and late to wake.

The average early bedtime was 9.20pm while early wakeups were 7am. Late bed times were around 10.40pm and late wake-ups 8.20am.

After 4 nights it was observed that children in both the groups early to bed/early to rise and late to bed/late to rise were getting the same amount of sleep (about 9 ½ hours), however the ‘latestops’ were more likely to be obese.

They were nearly twice as likely to be physically inactive and three times as likely to spend long periods in front of computers and TV screens. ‘Latestops’ spent nearly an hour longer watching TV, playing computer games or being online each day, mainly between 7pm and midnight.

The early to bed/early to rise group spent more than an hour a day being more physically active than ‘latestops’.

The study concluded that “Late bedtimes and late wake up times are associated with an unfavourable activity and weight status profile, independent of age, sex, household income, geographical remoteness, and sleep duration.”

Writer Helen Splarn. Editor Dr Ramesh Manocha.
Source: Olds TS; Maher CA; Matricciani L. Sleep duration or bedtime? Exploring the relationship between sleep habits and weight status and activity patterns. SLEEP 2011;34(10):1299-1307.