Add up how far short of your own nightly target you have slept over a week. The total is worked out from the figures you type. It is a framing number, not a diagnosis, and not a debt you can simply repay.
Add up how far short of your own target you have slept over a week. This is a framing figure, worked out from the numbers you type. It is not a diagnosis, and the total is not a debt you can pay back one for one.
How to pick this
Seven to nine hours is the range commonly cited for healthy adults. Pick the figure you actually feel rested on. The tool measures your week against your own target, not against ours.
What counts
Time actually asleep, as best you know it, not time in bed. Rough is fine. Leave a night blank if you would rather not estimate it, and it is left out of the total.
Your sleep shortfall this week
Enter some nights above
Why this number
This is simple subtraction: for each night you gave a figure, the tool takes your target minus what you slept, counts only the nights you fell short, and adds those up. It is arithmetic on your own numbers, not a measurement of anything in your body.
Average shortfall per night
Enter some nights above
Why this number
The same total spread across the nights you entered. A small nightly gap adds up across a week, which is the only thing this figure is meant to show.
Sleep debt is a metaphor, not a bank balance. You cannot assume an hour lost is an hour you can simply repay at the weekend. In a randomised study of recurrent short sleep, “ad libitum weekend recovery sleep fails to prevent metabolic dysregulation”, and over the recovery weekend people slept only about an hour more a night than their baseline. Treat a rising total as a reason to protect your nights this week, not as a number you can clear on Saturday.
Sources: Depner et al. 2019, weekend recovery sleep; AASM and SRS sleep-duration consensus. Background: Can You Catch Up on Sleep on Weekends?
Everything is worked out in your browser. Nothing you type is sent to us or to anyone else.
Read this before you trust the number
The total here is arithmetic on your own estimates, nothing more. “Sleep debt” is a metaphor, not a bank balance: research on recurrent short sleep found that weekend catch-up does not undo the effects, and people slept only about an hour more a night over the recovery weekend.
Persistent trouble sleeping, loud snoring with daytime sleepiness, or sleep that is unrefreshing however long you spend in bed are worth raising with a clinician. See the medical disclaimer.
Why the tool uses your target, not ours
Seven to nine hours is the range commonly cited for healthy adults, but the right figure within it is personal. So the tool asks for your target and measures your week against that, rather than asserting a single number you have to need. Everything it reports is your target minus what you slept, added up.
Why catch-up does not clear the total
It is tempting to read a rising total as something you can pay off on Saturday. The evidence does not support that. In a randomised study, ad libitum weekend recovery sleep failed to prevent the metabolic changes caused by short weekday nights. The useful move is protecting this week’s nights, not banking on the weekend.
Common questions
Is sleep debt a real medical measurement?
No. It is a useful way to notice a pattern, but your body does not keep a ledger you can settle. Treat a large total as a prompt to prioritise sleep, not as a number with clinical meaning.
Should I count time in bed or time asleep?
Time actually asleep, as best you can estimate it. Rough is fine. The tool is about the shape of your week, not decimal precision.
Can I just sleep in at the weekend to fix it?
You can feel better for it, but a study of recurrent short sleep found weekend recovery did not prevent the metabolic effects, and people gained only about an hour a night back. Consistent nights beat a big weekend.