Sleep Debt Calculator
Sleep debt is the gap between the sleep you need and the sleep you actually get. Enter how long you slept each night this past week to see how much you owe, and how long it takes to pay back.
Your sleep this week
Hours of actual sleep per night, e.g. 6.5 for six and a half hours.
Sleep debt this week
7 h
Average per night
7 h
Short nights
7 of 7
How to pay it back
- Sleep 1 hour longer each night: paid back in 7 nights.
- Sleep 30 minutes longer each night: paid back in 14 nights.
Go to bed earlier rather than sleeping in, and use the sleep calculator to pick a bedtime that ends on a full cycle.
What is sleep debt?
Every night you sleep less than your body needs, the shortfall carries over. Sleep 6 hours when you need 8, five nights in a row, and you're 10 hours behind by Friday. That running total is your sleep debt.
Most adults need 7 to 9 hours a night. If you're not sure where you fall, 8 hours is a reasonable starting point: if you still wake up tired after a week of 8-hour nights, try 8.5.
How to pay back sleep debt
- Move your bedtime 30 to 60 minutes earlier for a week or two instead of trying to recover in one night.
- Keep your wake-up time the same every day. Sleeping in late on weekends shifts your body clock and makes Monday harder.
- Use a short power nap to get through the afternoon while you catch up.
- Cut caffeine after lunch and screens in the last hour before bed so the extra time in bed turns into extra sleep.
Signs you're carrying sleep debt
- You can't wake up without an alarm, or you hit snooze every morning.
- You fall asleep within a few minutes of lying down.
- You sleep hours longer on days off.
- You struggle to focus or feel irritable by mid-afternoon.
More free sleep tools
Sleep Calculator
Best bedtime or wake-up time based on 90-minute sleep cycles.
Nap Calculator
When to set your alarm for a power nap or a full-cycle nap.
REM Sleep Calculator
When each REM period happens and how much REM sleep you get.
Jet Lag Calculator
How long jet lag lasts and how to shift your sleep before you fly.
Sleep Efficiency Calculator
What share of your time in bed you actually spend asleep.
Frequently asked questions
How is sleep debt calculated?
Multiply the sleep you need per night by the number of nights, then subtract the sleep you actually got. Need 8 hours and slept 6 hours a night for a week? That is 56 minus 42, so 14 hours of sleep debt. Longer nights count against shorter ones.
Can you catch up on sleep on the weekend?
Only partly. One long lie-in helps you feel better, but research suggests weekend recovery sleep does not fully undo the effects of a week of short nights, and sleeping in late shifts your body clock. Adding 30 to 60 minutes over several nights works better.
How much sleep debt is too much?
There is no official cut-off, but sleep experts recommend at least 7 hours a night for adults, and regularly getting less is linked to poorer focus, mood and long-term health. If you build up debt most weeks, the fix is a schedule that gives you enough sleep every night.
Do naps help pay back sleep debt?
A little. A 20-minute nap restores alertness for the afternoon, and a 90-minute nap adds a full sleep cycle. Naps are a short-term fix, though; consistent, longer nights are what clear sleep debt.