Last updated: March 2026
Frequently Asked Questions
Can you really catch up on sleep on the weekend?
Mostly no. Research from the University of Colorado showed that weekend recovery sleep does not reverse the metabolic damage of chronic weekday sleep deprivation — insulin sensitivity, inflammation markers, and circadian disruption persist. Small debts (1-2 hours) can be recovered with 1-2 nights of extra sleep, but chronic 5+ hour debts require weeks of consistent 8+ hour nights to fully resolve.
What's a normal amount of sleep?
Adults need 7-9 hours per night for optimal function. Teenagers need 8-10. Chronic sleep under 7 hours correlates with higher rates of heart disease, obesity, depression, and cognitive decline — this isn't marketing copy, it's decades of peer-reviewed research.
How is sleep debt calculated?
Debt = (ideal hours × days) − (actual hours slept). If you aim for 8 hours and slept 6.5, 7, 5.5, 7, 6, 8, 9 last week — that's 49h total, vs 56h ideal, = 7 hours of debt. This tool shows you the math and recovery timeline.
Why does one bad night affect me so much?
Sleep debt compounds. One night of 6 hours vs 8 hours has measurable cognitive effects (roughly equivalent to a 0.05% BAC). Three consecutive nights push you closer to 0.08%. Your brain feels 'fine' but reaction time, decision-making, and memory consolidation are all degraded.
Are naps a replacement for sleep?
Short naps (20-30 min before 3pm) can boost alertness without creating sleep-inertia grogginess, but they're a supplement — not a replacement for consolidated nighttime sleep. Long naps after 3pm interfere with your ability to fall asleep that night, which compounds the debt.