Sleep Debt Calculator

Sleep debt adds up. If you need 8 hours but only get 6, you're 2 hours short. Calculate your total over the last five nights.

How many hours did you actually sleep over the last 5 nights?

Your Total Sleep Debt

9 hours

That's about 1.8 h a night short. Short nights add up, and attention and mood usually feel it first. Keep your wake time steady and go to bed a little earlier for a few nights rather than sleeping in.

Educational, not medical advice. If sleep problems persist, talk to a doctor.

Let ARC track the debt for you

Log last night's sleep in one tap and ARC tracks a real sleep debt against your own target. When it builds up, ARC switches to a recovery plan for up to three days, changing your daily sentence, your one ask and your caffeine cutoff.

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What is Sleep Debt?

Sleep debt is the difference between the sleep your body needs and the sleep you actually get. It adds up. If you need 8 hours a night but only get 6 on Monday, you start Tuesday 2 hours short.

Why Weekend Lie-ins Only Partly Help

Sleeping in for hours on Saturday and Sunday shifts your body clock later and creates social jetlag, which makes it harder to fall asleep on Sunday night and makes Monday harder. Catch-up sleep does reduce daytime sleepiness, but in a lab study it didn't prevent the metabolic effects of repeated short nights (Depner et al. 2019, Current Biology). More on this in the sleep debt myth.

How to Recover from Sleep Debt

  1. Keep Your Wake Time Steady: Try not to sleep in by more than about 60 minutes at weekends, even when you're tired.
  2. Add Sleep at the Start of the Night: Go to bed 30-60 minutes earlier than usual rather than waking up later.
  3. Nap Early and Short: A 20-30 minute nap before about 3:00 PM can take the edge off without eating into tonight's sleep pressure.

Frequently asked questions

How do you calculate sleep debt?

Multiply the sleep you need per night by the number of nights, then subtract the sleep you actually got. If you need 8 hours and slept 7, 6, 7, 5 and 6 hours over five nights, you're 9 hours short.

Can you catch up on sleep at the weekend?

Partly. Extra sleep reduces daytime sleepiness, but a lab study found weekend recovery sleep didn't prevent the metabolic effects of repeated short nights (Depner et al. 2019, Current Biology). Sleeping in late also shifts your body clock, which makes Sunday night harder.

How long does it take to recover from sleep debt?

Usually a few nights of slightly longer sleep, not one long lie-in. Going to bed 30 to 60 minutes earlier while keeping your wake time steady is the gentlest way to pay it back.

How much sleep do I need?

Most adults need 7 to 9 hours. The best guide is how much you sleep on a long holiday once the first few catch-up nights are over, when you wake without an alarm and feel rested.

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