What is sleep debt?
Sleep debt is the difference between the sleep you need and the sleep you actually get. If you need 8 hours and sleep 6 hours each weeknight, you build up 10 hours of debt by Friday.
Research shows that sleep loss adds up. In a well-known 2003 study, people who slept 6 hours a night for two weeks performed as badly on attention tests as people who had gone without sleep for one or two full nights, yet they felt only slightly sleepy. So you may not notice how much it is affecting you.
How to pay it back
- Go to bed earlier, not later. Adding 30 to 60 minutes a night is easier on your body clock than sleeping in.
- Keep your wake-up time steady. Sleeping in by more than about 2 hours at the weekend shifts your body clock and makes Monday harder.
- Use short naps. A 20-minute nap in the early afternoon can help on a bad day. See the nap calculator.
- Don’t expect one long sleep to fix it. Studies suggest that a weekend lie-in helps a little, but doesn’t fully undo a week of short sleep.
Frequently asked questions
Can you catch up on lost sleep?
Partly. Extra sleep over several nights helps you feel better, but research suggests weekend recovery sleep doesn’t fully reverse the effects of a week of short sleep. The best fix is to sleep enough most nights.
How long does it take to recover from sleep debt?
It depends on how much you have built up. Adding up to an hour a night, the calculator shows how many nights it would take. Recovering from long-term sleep loss can take several weeks.
How do I know how much sleep I need?
Most adults need 7 to 9 hours. On holiday, after a few days, note how long you sleep without an alarm: that is a good guide to your natural need.
For general information only, not medical advice. If you often feel tired despite enough sleep, snore loudly, or have trouble sleeping most nights, talk to a doctor.