Sleep debt calculator
The short answer: sleep debt is the gap between what you need and what you got, and it compounds across the week. Enter your last seven nights - we'll show the damage and an honest repayment plan (spoiler: one Saturday lie-in won't do it).
What is sleep debt, exactly?
Sleep debt is the running total of hours you fell short of your need. It behaves less like a bank balance and more like jet lag: performance and mood degrade in proportion to the accumulated gap, and in lab studies people running a 2-hour nightly deficit performed like they'd pulled an all-nighter within 10 days - while rating themselves "fine." The subjective feeling adapts; the impairment doesn't. That's what makes debt sneaky.
Can you repay it on the weekend?
Partially. Recovery sleep repays some short-term debt, but studies show one weekend doesn't restore performance after a week of restriction - and sleeping in 2+ hours shifts your body clock later, handing you Sunday-night insomnia as interest. The honest plan: modest extra sleep nightly, a lie-in capped around an hour, and two weeks of consistency.
Your need isn't a chip you tap. It's a number you find.
This calculator assumes the need you picked. Claritips finds your real one: log hours and restfulness for two weeks and see where your mornings actually turn good - "restfulness on 7.5+ hour nights: 4.2★ vs 3.0★ under 7." No AI, just your own arithmetic.
Find your real number - free →