Sleep Debt Calculator
Track accumulated sleep debt over a week and see how many extra hours you'd need to recover.
What this calculates
Sleep debt is the cumulative gap between sleep you need and sleep you get. It builds across days and isn't fully recoverable with weekend lie-ins — studies show partial recovery only. This calculator tracks a 7-day window and shows total debt plus a realistic recovery estimate.
Formula & how it works
Daily debt = max(0, target_hours − actual_hours). Total debt = sum of daily debts across N days. Realistic recovery: weekend can recover ~30-50 % of weekly debt. Full recovery requires consistent target sleep for 1-2 weeks.
Worked example
Target 8 h/night. Mon 6, Tue 6.5, Wed 7, Thu 5, Fri 7, Sat 9, Sun 9. Daily debt: 2, 1.5, 1, 3, 1, 0, 0. Total debt = 8.5 hours. Even with weekend recovery (~3 hours regained), you're heading into the next Monday with ~5.5 hours debt — exhaustion accumulates.
Frequently asked questions
Can I 'catch up' on weekends?
Partially. Research shows weekend recovery sleep reverses some performance deficits but not metabolic and immune markers. The healthier path is consistency, not catch-up.
How much sleep do I need?
Adults: 7-9 h. Teens: 8-10 h. Older adults: 7-8 h. Individual variation — some genuinely thrive on 6 h, but they're rare (real short-sleepers are <3 % of population).
Is one bad night damaging?
Performance dips next day (reaction time, mood, decision-making). Lasting effects start with multiple consecutive nights. A single 4-hour night is mostly recoverable; a week of 4 hours has real cognitive and metabolic impact.
What about naps?
20-30 min naps reduce sleep debt without sleep inertia. Longer naps (60-90 min) work but can disrupt nighttime sleep. Avoid napping after 3 PM if you have evening sleep difficulty.