Sleeping in on the weekend can help the body recover mildly during those two days, study suggests. But the effects don’t last. As part of the study, the researchers enlisted 36 healthy adults age 18 to 39 to stay for two weeks in a laboratory, where their food intake, light exposure and sleep were monitored.
After baseline testing, the volunteers were divided into groups. One was allowed plenty of time to sleep–9 hours each night for 9 nights. The second was allowed 5 hours per night over that same period. The third slept no more than 5 hours nightly for 5 days followed by a weekend when they could sleep as much as they liked before returning to 2 days of restricted sleep.
Both sleep-restricted groups snacked more at night, gained weight and saw declines in insulin sensitivity during the study period. While those in the weekend recovery group saw mild improvements (including reduced nighttime snacking) during the weekend, those benefits went away when the sleep-restricted workweek resumed.
“In the end, we didn’t see any benefit in any metabolic outcome in the people who got to sleep in on the weekend,” said Chris Depner, lead author of the study.
The results were published in the Journal of Current Biology.
On some measures, the weekend recovery group showed worse outcomes. For instance, in the group which had their sleep restricted the whole time, whole-body insulin sensitivity declined by 13 per cent. In the weekend recovery group, it worsened by 9 to 27 per cent, with sensitivity in the muscles and liver scoring worse than the other groups.
“It could be that the yo-yoing back and forth – changing the time we eat, changing our circadian clock and then going back to insufficient sleep is uniquely disruptive,” researchers suggested.
Even when given the chance, people found it difficult to recover lost sleep. While they gained some ground Friday and Saturday, their body clocks shifted later Sunday night making it hard to fall asleep even though they had to get up early Monday.
In the end, the recovery group got just 66 minutes more sleep on average. Men made up more lost sleep than women.