Your sleep debt is the sleep you've missed against your sleep need over the last 14 nights, with the most recent nights counting most. It's on the Sleep page, beside your sleep score, and its own page shows how it moved night by night.
How it works
Each night, NOYU compares how long you slept with your sleep need. A short night adds to your debt, and a long night pays some of it back. Last night counts most, and each night before it a little less, so a run of short nights shows quickly and fades over about two weeks once you sleep well again.
- Naps count. Sleep during the day is added to that day's total, so a nap lowers your debt.
- A night you didn't sleep (I didn't sleep) counts as no sleep, so it adds your whole need.
- A night with no data is left out, and the other nights count for it. The page says so, for example "From 13 of the last 14 nights".
- It never goes below 0. A long night pays debt back, but you can't bank sleep ahead of a short night.
NOYU shows your debt once it has at least 5 of your last 14 nights. Until then the figure is hidden, and after a long gap the tile says how many more nights it needs.
Low, moderate and high
| Level | Sleep debt |
|---|---|
| Low | Under 5 hours |
| Moderate | 5 to 10 hours |
| High | Over 10 hours |
Research suggests the effects build gradually rather than switching on at a line. Several nights of about an hour short each can lower alertness and reaction time, often without you feeling very sleepy, and one long night doesn't fully undo it.
What moved it
On the sleep debt page, Behind your sleep debt lists your recent nights with how long you slept, and whether each night raised or lowered your debt. Trends shows what it was a week, a month and three months ago.
Your sleep need sets the target
Your debt is measured against your sleep need, 8h 15m until you change it or take NOYU's figure. Change your need and NOYU works out your debt again with the new one, for past days too, so the chart stays comparable. See Your sleep need.
Paying it back
- Go to bed a little earlier for several nights rather than sleeping very late once. A consistent bedtime helps your sleep score too.
- A short nap early in the afternoon helps, and counts towards your debt.
- Expect it to take a few days. Research suggests recovering from a week of short sleep takes more than a night or two.
Why it differs from other apps
Rise, Oura, WHOOP and Garmin each work out sleep debt or sleep need their own way, so their figures won't match NOYU's. NOYU's uses your own sleep need and your nights as NOYU records them, including the nights you add or edit yourself.
