I get this question a lot. I think it's because people expect to hear something different from the truth: NO, you can't just pay off a sleep debt by sleeping late on the weekend. Sorry. The proof? Check out the following studies of late, which have changed some of the conventional thinking of many of us in the world of sleep science:
- In 2003, scientists at the Walter Reed Army Institute of Research examined the cognitive effects of a week of poor sleep, followed by three days of sleeping at least eight hours a night. The scientists found that the "recovery" sleep did not fully reverse declines in performance on a test of reaction times and other psychomotor tasks, especially for subjects who had been forced to sleep only three or five hours a night.
- In a similar study in 2008, scientists at the Karolinska Institute in Stockholm found that when subjects slept four hours a night over five days, and then "recovered" with eight hours a night over the following week, they still showed slight residual cognitive impairments a week later, even though they reported no sleepiness.
- Another study done this year at Walter Reed found that people recovered much more quickly from a week of poor sleep when it was preceded by a "banking" week that included nights with 10 hours of shuteye.
The good news in this latest study, and a change from prior thinking, is that it appears you can prepare for an upcoming sleep debt by banking some hours of sleep. In other words, if you know you have a week of little sleep ahead of you, try loading up on sleep beforehand, not simply afterward. However it should be noted that you are likely only paying off a bit of sleep debt, to bring your reserves back to normal, before depleting them again.
The bad news, of course, is that it's not so easy to pay off a sleep debt in a single night of solid sleep. And the effects of that sleep deprivation can last a lot longer than what you'd imagine. (We all just got an extra hour last a few weeks ago when the time changed. How much better off are you today?)
The lesson: avoid chronic sleep deprivation entirely, and when life gets in the way of that goal, then plan for it. Use weekends to prepare for a long work week rather than trying to make up for them.
Michael J. Breus, PhD
This article on sleep debt is also availabe at Dr. Breus's official blog, The Insomnia Blog.