๐ด Sleep Debt Calculator
This is only a general guideline. If you have ongoing sleep concerns, consult a doctor.
Enter your recommended sleep target and your actual sleep hours for the last 7 days to calculate your total accumulated "sleep debt" โ the sum of your shortfalls. A quick way to visualize how much sleep loss has built up.
How to use
- Enter your personal recommended sleep target (in hours).
- Enter your actual sleep hours for each of the last 7 days.
- Your total sleep debt โ the sum of shortfalls on days you slept less than your target โ is calculated automatically.
How the calculation works
Sleep debt is the build-up of sleep you missed compared with the amount you need. Enter seven days of sleep and this tool calculates your sleep debt for the week. Shortfall each day = sleep needed โ sleep that day (0 if you slept enough) Weekly sleep debt = total of the seven shortfalls Hours slept beyond your need are shown separately as extra sleep rather than subtracted from the debt, because "catch-up" sleep is thought not to fully repay a sleep debt. Japan's Ministry of Health, Labour and Welfare (Sleep Guide 2023) recommends that adults get at least 6 hours as a guide, securing the sleep they need. How much sleep you need varies by person and with age.
Worked example
Sleep needed: 8 hours The week: 7, 6.5, 7.5, 6, 8, 9, 7 hours (51 in total) Daily shortfall: 1, 1.5, 0.5, 2, 0, 0, 1 hours Weekly sleep debt: 6 hours Extra sleep: 1 hour (the 9-hour night) Against the 56 hours needed, you slept 51.
Things to be aware of
- Sleeping in for long stretches at the weekend can shift your body clock and make Monday mornings harder ("social jet lag"). Going to bed a little earlier on weeknights works better.
- If you are very sleepy during the day despite enough sleep, it could be a condition such as sleep apnoea. See a doctor.
- To find how much sleep you need, record how long you sleep on days off when you wake without an alarm.
FAQ
What does "sleep debt" mean?
It's the idea that when you consistently sleep less than your recommended target, the shortfall accumulates like a debt over time. Built-up sleep debt is associated with daytime sleepiness and reduced concentration.
What should I set as my recommended sleep target?
For adults, roughly 7-9 hours per night is a commonly cited general guideline, but individual sleep needs vary. Use whatever amount leaves you feeling your best.
How are days where I overslept handled?
A day where you slept more than your target counts as zero debt for that day, and the excess is shown separately as "surplus" sleep. Keep in mind that oversleeping doesn't necessarily cancel out previously accumulated sleep debt in a simple 1:1 way.