Sleep Debt Calculator
Enter how many hours you slept each of the last 7 nights to see your accumulated sleep debt against your age-based need — and how to repay it.
Around 8.5 h of accumulated shortfall. At this level focus, mood and reaction time measurably degrade. Bank an extra 1–1.5 h/night over the next several nights and prioritise an early, consistent bedtime.
Educational estimate, not medical advice. Sleep need is individual and the 7-night window reflects recent, practically-repayable debt — not lifetime deprivation. Consistent sleep and wake times matter as much as total hours.
Stop guessing your hours
ONDA Life tracks your actual sleep and recovery automatically — your real debt, updated every morning, with a plan to repay it.
Download ONDA Life on the App Store →Recommended sleep by age
| Age | Recommended nightly sleep |
|---|---|
| 14–17 | 8–10 h |
| 18–25 | 7–9 h |
| 26–64 | 7–9 h |
| 65+ | 7–8 h |
Sources & methodology
Age-based sleep-need ranges come from the National Sleep Foundation recommendations (Hirshkowitz 2015) and the AASM/Sleep Research Society adult consensus of at least 7 hours (Watson 2015). Debt is the cumulative shortfall — the sum over your last 7 nights of (need − actual sleep). The "debt" framing rests on Van Dongen 2003, which showed that chronic short sleep degrades performance dose-dependently and that the deficit is not fully repaid by one lie-in. Need is individual; these bands are population guidance, and your own daytime alertness is the practical check.
- [1] Hirshkowitz M, Whiton K, Albert SM, et al. (2015). National Sleep Foundation's sleep time duration recommendations: methodology and results summary. Sleep Health, 1(1):40–43.
Primary basis for the age-banded sleep-need ranges used to compute your debt.
- [2] Watson NF, Badr MS, Belenky G, et al. (2015). Recommended amount of sleep for a healthy adult: a joint consensus statement of the AASM and Sleep Research Society. Sleep, 38(6):843–844.
The ≥7 hours/night adult recommendation that anchors the adult need band.
- [3] Van Dongen HPA, Maislin G, Mullington JM, Dinges DF (2003). The cumulative cost of additional wakefulness: dose-response effects from chronic sleep restriction. Sleep, 26(2):117–126.
Evidence that sleep debt accumulates dose-dependently and is not erased by a single long night.
Common questions
Where do the sleep-need numbers come from?
The age-based need ranges follow the National Sleep Foundation recommendations (Hirshkowitz 2015) and the AASM/Sleep Research Society ≥7-hour adult consensus (Watson 2015); the idea that debt accumulates comes from Van Dongen (2003). Full citations are in the Sources section on this page. Sleep need varies between individuals — treat the bands as population guidance.
What is sleep debt?
Sleep debt is the running total of the gap between how much sleep you need and how much you actually get. Lose an hour a night for five nights and you carry roughly five hours of debt — which degrades focus, mood, glucose control and reaction time even if you feel "used to it".
Can you catch up on sleep?
Partly. Recent debt (the last week or so) is largely repayable with a few longer nights — ideally by going to bed earlier rather than sleeping in, which shifts your body clock. Chronic, months-long deprivation is not fully reversible in a weekend; it rebuilds gradually with consistent adequate sleep.
How much sleep do I actually need?
For most adults 18–64, the consensus recommendation is 7–9 hours; 7–8 hours at 65+. Teens need 8–10. Genuine "short sleepers" who thrive on under 6 hours are rare (<1% of people) — most who think they are one are simply adapted to chronic debt.
Why does this only count the last 7 nights?
Recent debt is the part you can practically repay and that most affects how you feel and perform right now. The body does not keep an infinite ledger — older deficits partially reset, so a rolling weekly window is the useful, honest number to act on.
Is sleeping in on weekends a good fix?
It helps with acute debt but has a cost: large weekend lie-ins create "social jet lag", shifting your clock so Monday feels worse. Better to repay debt with consistent, slightly earlier bedtimes through the week and cap weekend catch-up to ~1 hour later than usual.