This calculator is for general information and education. It is not medical advice and does not replace the judgment of a doctor, nurse or pharmacist who knows the full clinical picture.
What sleep debt is
Sleep debt is the gap between the sleep your body needs and the sleep you actually get. Most adults need 7 to 9 hours a night. Losing an hour each workday adds up to five hours by Friday, and the effects accumulate: slower reactions, poorer memory and mood, more cravings and a higher risk of accidents.
How the calculator works
Enter the sleep you need and the hours you slept on each of the last seven nights. The calculator adds them up, subtracts them from seven times your need, counts the nights under 7 hours and estimates how many nights of extra sleep would pay the debt back.
Example
Needing 8 hours a night, with 6.5, 6, 7, 6.5, 6, 8.5 and 9 hours over the week:
- total: 49.5 hours instead of 56;
- sleep debt: 6.5 hours;
- average: 7.1 hours a night, with 4 nights under 7 hours;
- going to bed an hour earlier for about a week would make it up.
How much sleep do you need?
The American Academy of Sleep Medicine recommends at least 7 hours for adults. Teenagers need 8 to 10 hours, and school-age children 9 to 12. A simple test: on a vacation with no alarm, after the first few days, the amount you sleep naturally is close to your need.
Paying back the debt
- Extend sleep gradually: 30 to 60 minutes earlier to bed each night works better than one very long lie-in.
- Weekend catch-up helps partly, but research suggests it does not fully reverse the effects of a week of short sleep, and sleeping in late shifts your body clock.
- Short naps of 20 minutes, before mid-afternoon, can restore alertness without hurting night sleep.
- Long-term debt built over months is not repaid hour for hour; the goal is to return to enough sleep every night.
Better sleep habits
- Keep the same wake-up time every day, including weekends.
- Get daylight in the morning and dim screens in the evening.
- Avoid caffeine after early afternoon and alcohol close to bedtime.
- Keep the bedroom cool, dark and quiet.
When to see a doctor
If you sleep enough hours but still feel exhausted, snore loudly, stop breathing during sleep, or fall asleep during the day, talk to a doctor. Sleep apnea, insomnia and other sleep disorders are common and treatable.