Sleep Debt Calculator
Calculate how much sleep debt you have built up and how long it will take to recover. Understand the health impact of chronic sleep restriction.
Sleep Debt Guide
What is Sleep Debt?
Sleep debt (or sleep deficit) is the cumulative difference between the sleep you need and the sleep you get. Losing 2 hours per night for a week creates 14 hours of sleep debt. Research (particularly Matthew Walker's work at UC Berkeley) shows that even modest chronic sleep restriction — 6 hours per night for 10 days — produces cognitive impairment equivalent to 24 hours of total sleep deprivation. Crucially, people who are chronically sleep-deprived often cannot accurately gauge their own impai
Can You Repay Sleep Debt?
Short-term sleep debt (a few nights) can be substantially repaid with extra sleep over a few days. However, chronic sleep debt (months or years) creates long-term biological changes that cannot be fully recovered simply by sleeping more. A 2021 study found that after two weeks of 6-hours-per-night sleep, participants needed more than 3 days of recovery sleep to restore cognitive performance. The weekend lie-in strategy ('social jet lag') partially compensates but disrupts the circadian rhythm, c
Health Consequences of Sleep Debt
Chronic sleep restriction below 7 hours is associated with: 45% increased risk of cardiovascular disease, 300% increased risk of catching a cold (immune suppression), significantly elevated cortisol (stress hormone) and reduced leptin (satiety hormone, driving weight gain), impaired glucose tolerance (increased type 2 diabetes risk), reduced testosterone (men: equivalent of 10 years of ageing after 1 week at 5 hours/night), and impaired memory consolidation, learning, and emotional regulation.
Building Better Sleep Habits
The most evidence-backed approaches to improving sleep: consistency — the same wake time every day (including weekends) is more important than bedtime. Temperature — bedroom at 16–19°C promotes deep sleep. Light — darkness within 1 hour of bed and bright light within 30 minutes of waking. Caffeine — none after noon (5–6 hour half-life means 3pm coffee is still 50% active at 8pm). Alcohol — impairs REM sleep even in small amounts, despite feeling sedating. Phone use — the blue light wavelength su
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