Recovery
As of 2026-04-24
How Sleep Debt Calculator works
Methodology for the Sleep Debt Calculator: formulas, coefficients, data sources, assumptions, and known limitations.
Scope
Tracks 7 nights of sleep, computes accumulated sleep debt vs target, and projects a recovery timeline.
Formula
debt = sum(target_h - actual_h for past 7 nights). Recovery = ~1 recovery night per ~2 h accumulated debt.
Coefficients
| Parameter | Value | Note |
|---|---|---|
| Adult target (NSF) | 7–9 h/night | |
| Rough recovery rate | ~1 extra hour per recovery night |
Data sources
- Hirshkowitz M, Whiton K, Albert SM, et al. National Sleep Foundation's sleep time duration recommendations: methodology and results summary. Sleep Health. 2015;1(1):40-43. — PMID 29073412. Source of the 7-9 h adult target.
- Van Dongen HPA, Maislin G, Mullington JM, Dinges DF. The cumulative cost of additional wakefulness: dose-response effects on neurobehavioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation. Sleep. 2003;26(2):117-126. — PMID 12683469. Foundational sleep-debt dose-response study.
- Rupp TL, Wesensten NJ, Bliese PD, Balkin TJ. Banking sleep: realization of benefits during subsequent sleep restriction and recovery. Sleep. 2009;32(3):311-321. — PMID 19294951. Evidence on the recovery-night dose required to repay debt.
Assumptions
- Sleep times are honest; self-report tends to overstate actual sleep by 20–30 minutes.
Approximation range
Chronic restriction (< 6 h/night) produces measurable cognitive deficits within 2 weeks.
Limitations
- A calculator cannot diagnose insomnia or sleep apnea.
Reproducibility
Target 8 h, actual 6, 7, 6.5, 7, 5, 8, 7.5 → debt = 56 - 47 = 9 h. Recovery ~5 nights of +1.8 h each.
Change log
- 2026-04-24: methodology page first published.
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