It used to be thought that sleep was a commodity you couldn’t catch up on. Pull an all-nighter to cram for a test in college, or get up early to polish off one more project before work, and you could expect to be carrying the cognitive and physical effects of that sleep loss forever.
Now, however, the Sleep Foundation has seemed to indicate that it takes around nine days to eliminate sleep debt from one night. To recover from a prolonged pattern of not enough sleep, a Polish university suggests that it takes far, far longer than that.