Banking sleep to save energy for later? To most people, this idea probably sounds too good to be true. At the very least, it probably seems to defy common sense and or runs counter to the way we think our bodies work. However, it actually turns out that banking sleep is possible—within limits.

A great deal of research has been conducted on this subject.  In one particular study, American scientists invited a number of volunteers to adjust their sleep patterns so that researchers could observe the effects. For a week, half of the volunteers were permitted to sleep more than usual, and the remaining volunteers were made to sleep according to their usual pattern.

“After this week of either extended or habitual sleep per night, all the volunteers came to the lab and they were given three hours of sleep, per night, for a week,” says Tracy Rupp of the Walter Reed Army Institute of Research. The volunteers were then assigned tasks of varying difficulty, and those who had banked their sleep were more unaffected throughout the sleep restriction.

Rupp elaborates: “They showed less performance deterioration with regards to reaction time and alertness than the group that had been given the habitual prior sleep.”

The study also revealed that a week after the experiment, the banked sleepers were recuperating faster from deficiency of sleep than the others were. Rupp again: “What we’re basically saying is if you fill up your reserves and pay back your sleep debt ahead of time, you’re better equipped to deal with the sleep loss challenge.”

While these results may sound great, there are limits to what banking sleep can do for you. “It’s a strategy that’s only partially successful,” explains Michael J. Breus, Ph.D., in the November 2013 issue of Psychology Today. “New research indicates that although some of the negative effects of a week of insufficient sleep can be remedied with extra sleep on the weekend, others cannot. Researchers at Penn State University College of Medicine studied the effects of weekend recovery sleep after a week of mild sleep deprivation. They found that make-up sleep on the weekends erased only some of the deficits associated with not sleeping enough the previous week.”

Banking sleep isn’t limited to sleeping longer nights. Naps can be extremely effective as well—within limits, of course. According to Science Focus, “A 1991 study at Wright State University in Dayton, Ohio found that after an ordinary night’s sleep, subjects could take an extra nap in the afternoon and then work through the night with greater alertness that a control group who didn’t nap. The study also found that performance is proportional to the length of the nap—but the effect doesn’t last.

After a second consecutive night without sleep, all of the subjects performed equally badly, regardless of how much sleep they had initially. It may be that all of us are normally slightly sleep-deprived and one really good night’s sleep will bring us back up to 100%, but that the ‘tank’ isn’t big enough to buffer us against more than one all-nighter.”

The practical uses of banking sleep go beyond needing to pull an all-nighter before finals or a big presentation at work. Dr. Winter, a member of the American Academy of Sleep Medicine, puts it thusly: “If you knew you were going to give birth on a particular day, for example, you could sleep for 10 hours a day for multiple days before the event, and be fine.”

Lastly, it is important to consider the host of negative effects of sleep deprivation. Memory loss, obesity, and even early death comprise some of these consequences. The moral of the story here is that banking sleep in advance may actually be a reasonable short-term strategy for coping with an isolated event (like giving birth). However, the best long-term strategy for staying healthy and performing well is to get a good night’s sleep as consistently as possible.