Sleep debt calculator
Sleep debt is the running total of sleep you owe your body. Enter how many hours you slept each of the last seven nights and how much you need, and this tool shows your accumulated deficit — plus a realistic plan to pay it back.
How sleep debt is calculated
For each night, we subtract how long you slept from how much you need. Nights where you slept less add to your debt; nights where you slept more help pay it down. Add up all seven nights and you get your weekly sleep debt — the total number of hours you’re currently running behind.
A small debt of an hour or two is normal and easily recovered. Once you’re carrying five-plus hours, the effects start to show: slower reaction time, worse focus, low mood, stronger cravings, and a weaker immune system. The tricky part is that your sense of tiredness levels off even as your performance keeps dropping — so you can feel “fine” while functioning well below your best.
How to pay back what you owe
- Add sleep gradually. Extend your nights by 30–60 minutes rather than attempting one giant catch-up sleep. Go to bed earlier instead of waking later.
- Keep your wake time fixed. A stable wake time — weekends included — protects your body clock. Repay debt from the bedtime side.
- Avoid the weekend lie-in trap. Sleeping in by several hours causes “social jetlag” that wrecks Sunday night and Monday morning.
- Make recovery sleep count. Time it in full 90-minute cycles so you wake refreshed, not groggy.
When you’re ready to plan a recovery night, the sleep cycle calculator turns your wake-up time into bedtimes built from complete cycles, and our full sleep debt guide goes deeper on recovery.