Sleep debt calculator
Log how long you actually slept each night this week. We'll total the gap against the sleep you need and suggest a realistic way to pay some of it back.
Last 7 nights
Sleep debt this week
8 h 15 min
Average: 6 h 49 min a night vs. 8 h needed.
Payback plan: go to bed about 1 h earlier than usual for the next 9 nights.
What sleep debt is
Sleep debt is the running difference between the sleep you need and the sleep you get. Lose an hour a night for a working week and you're five hours short by Friday.
The effects accumulate. In a well-known experiment by Van Dongen and colleagues (2003, Sleep), people restricted to six hours a night for two weeks performed on attention tests as badly as people kept awake for a full night — while rating themselves only slightly sleepy.
Can you catch up?
Partly. One or two longer nights help you feel better, but studies suggest weekend lie-ins don't fully restore attention or undo all the effects of a short week, and big weekend shifts cause "social jet lag" on Monday.
- Add 30–60 minutes a night for a week rather than one huge lie-in.
- Move bedtime earlier, keep the alarm the same.
- An early-afternoon 20-minute nap can take the edge off.
- Then fix the cause: a bedtime that fits your need, from the bedtime calculator.
Questions people ask
How do you calculate sleep debt?
Subtract the hours you actually slept from the hours you need, for each night, and add them up. With an 8-hour need, sleeping 6.5 hours five nights running is 7.5 hours of debt.
How long does it take to recover from sleep debt?
A few nights of extra sleep restore how you feel from a short-term debt, but research suggests full recovery of attention can take longer. Aim for an extra 30–60 minutes a night rather than one long lie-in.
Can I pay off sleep debt on the weekend?
Partly. Weekend catch-up sleep helps but does not fully reverse the effects of a short week, and sleeping in late shifts your body clock, making Monday harder.
Is my data saved?
Your nights and need are stored only in this browser (localStorage) so the page remembers them. Clear them on the privacy page at any time.