Sleep debt is the running total of missed sleep - an hour short a night is 7 hours down by Friday.
Its treacherous property is adaptation: sleepiness plateaus after a few short nights, so you feel adjusted while reaction time, attention, and judgment stay impaired - the debt stops announcing itself. Repayment: acute debt lifts with a few long nights; chronic debt takes weeks of consistent sleep, and some costs are not fully reversible. The CDC counts under 7 hours as insufficient sleep for adults.
What to do
Common questions
What is sleep debt?
Sleep debt is the running total of the gap between the sleep you need and the sleep you get - lose an hour a night and you are 7 hours down by Friday, 30 by the end of the month. The treacherous property is adaptation: after a few short nights, subjective sleepiness plateaus - you feel like you adjusted - while objective performance keeps dropping: reaction time, attention, judgment, and mood regulation all stay impaired. That is why debt is dangerous: it stops announcing itself. The costs show up in the CDC's insufficient-sleep framing (under 7 hours for adults) and its links to heart disease, weight gain, and accidents. Repayment mechanics: acute debt from a rough week lifts with a few nights of extended sleep; chronic debt built over months takes weeks of consistent adequate sleep, and some costs are not fully reversible - the argument for never letting it build. The practical moves: guard a floor, keep the same wake time, and treat the weekend crash as a debt statement, not a treat. Pymander, a free AI doctor available 24/7 by text, can help you audit your own balance.