Calculator

Sleep Debt Calculator

Track your cumulative sleep deficit and estimate recovery time.

Most adults need 7-9 hours. If unsure, 8 is a reasonable default.

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Day 7 (last night)

How this works

Sleep debt is the cumulative difference between how much sleep you need and how much you actually get. While a single short night may feel manageable, the deficit accumulates and affects cognitive performance, immune function, metabolic health, and mood in measurable ways.

Research from the University of Pennsylvania and Walter Reed Army Institute showed that restricting sleep to 6 hours per night for two weeks produced cognitive impairment equivalent to two consecutive nights of total sleep deprivation, and that subjects consistently underestimated their own impairment.

Recovery is not one-to-one. You do not need to "repay" every lost hour. Studies suggest that extending sleep by 1-2 hours per night over several days is more effective than one marathon catch-up session. The recovery estimate here uses a gradual model (adding ~1 extra hour per night) rather than assuming full repayment.

References

Van Dongen HPA, et al. The cumulative cost of additional wakefulness. Sleep. 2003;26(2):117-126.

Kitamura S, et al. Estimating individual optimal sleep duration and potential sleep debt. Sci Rep. 2016;6:35812.

Banks S, Dinges DF. Behavioral and physiological consequences of sleep restriction. J Clin Sleep Med. 2007;3(5):519-528.