Sleep deprived don't catch up on sleep

EVANSTON, Ill., July 5 (UPI) -- U.S. researchers say that when animals are partially sleep deprived over consecutive days they no longer attempt to catch up on sleep, despite a sleep deficit.

Northwestern University researchers showed that repeated partial sleep loss negatively affects an animal's ability to compensate for lost sleep, and that the body responds differently to chronic sleep loss than it does to acute sleep loss.

The animals are getting by on less sleep but they do not try and catch up, so the ability to compensate for lost sleep is itself lost, which is damaging both physically and mentally, according to the findings published online by the Proceedings of the National Academy of Sciences.

The researchers kept animals awake for 20 hours per day followed by a four-hour sleep opportunity, over five consecutive days. At the end of the study, the animals were given three full days to sleep as much as they wanted, but didn't recover the lost sleep.