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Sleep Debt Calculator
Sleep debt is the gap between the sleep you need and the sleep you get. Enter your last seven nights to see where you stand — and how to claw it back.
Free · no signup · updated August 2026
Don’t just calculate it — track it
A number is a starting point. TempoLife takes your target and shows your real day against it — food logged by photo, barcode or search, plus weight, steps and fasting in one place. Free to start.
Why sleep debt compounds
Adults need roughly 7–9 hours a night; sleeping six against an eight-hour need doesn't feel dramatic on any single day, but it is a 14-hour hole by the end of the week — nearly two full nights. Lab studies show attention, glucose handling and mood degrade in step with cumulative debt, and — the uncomfortable finding — people under chronic restriction rate themselves as "fine" while their measured performance keeps falling.
Weekend lie-ins repay only part of the balance (this calculator counts surplus sleep at half value for that reason), because recovery sleep restores some functions faster than others and Monday's alarm restarts the cycle. The evidence-backed fix is boring and effective: move bedtime 30–60 minutes earlier at a fixed wake time until the debt is gone, keep caffeine out of the final 8 hours — the caffeine calculator shows your cutoff — and let a tracked sleep log make the trend visible.
Frequently asked questions
What is sleep debt?
The cumulative shortfall between your individual sleep need (typically 7–9 hours for adults) and what you actually sleep. It builds silently: six hours a night against an eight-hour need is a 14-hour hole by Sunday — nearly two full nights.
Can you catch up on sleep at the weekend?
Partially. Recovery sleep repays some of the deficit, but studies show attention and metabolism don't fully normalise after one long weekend lie-in, and Monday's early alarm restarts the cycle. The sustainable fix is a slightly earlier bedtime every night, not weekend binges.
How do I recover from sleep debt?
Add 30–60 minutes per night until the debt is gone, keep your wake time fixed, and protect the last hour before bed from screens and caffeine. This calculator shows how many nights of +1 hour your current debt needs.
Does napping count?
Yes — a 20–30 minute nap repays real minutes and boosts alertness without usually harming the night. Long or late naps can push your bedtime later, which deepens the original problem.
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Estimates for general information only, not medical advice. BMR/TDEE use the Mifflin-St Jeor equation; individual needs vary.
