Sleep debt calculator

How the calculator counts it

For each night you enter, it takes your goal minus the time you were actually asleep. A short night adds to the debt and a long night pays some back. With the example week above and an 8 hour goal, the weekdays add 7 hours 15 minutes and the weekend pays back 3 hours 30 minutes, which leaves 3 hours 45 minutes.

Three rules keep the number honest, and they're the same ones Sleep Tiles uses:

• One night pays back at most 2 hours. A 10 hour 30 minute Sunday against an 8 hour goal counts as 2 hours back, not 2 and a half.
• The total never drops below zero, so a long night now doesn't bank sleep for next week.
• Nights set to "Skip" are left out rather than counted as no sleep, so leave a night out if you don't know it.

Use time asleep, not time in bed. Lying awake doesn't count. Sleep debt, explained goes through the same example night by night.

Picking your goal

The American Academy of Sleep Medicine recommends 7 or more hours a night for adults on a regular basis, and says more than 9 hours may be appropriate for young adults. The calculator starts at 8 hours. Choose the amount that leaves you feeling rested, because a goal set too high makes the debt look worse than it is.

Paying it back

The plan spreads your debt over 7 nights, rounded to the nearest 15 minutes, and keeps it between 15 minutes and an hour earlier than your usual bedtime. For 3 hours 45 minutes that works out at 30 minutes, so a 10:30 PM bedtime becomes 10:00 PM. A bigger debt takes longer than a week at an hour a night, and that's fine.

Skip the typing

Entering two weeks by hand works once. If your Apple Watch, Oura Ring, WHOOP or Garmin saves your nights to Apple Health, Sleep Tiles works out this same two-week sleep debt every morning, shows what each night added or paid back, and suggests a bedtime for tonight.

Questions

What is sleep debt?

It's the gap between the sleep you need and the sleep you get, added up over several nights. Five short nights in a row add up to more debt than one.

Why does a long night only pay back 2 hours?

So one long weekend morning can't wipe out a week of short nights on paper. A week of short nights has to be paid back over more than one night.

Should I count time in bed or time asleep?

Time asleep. Your tracker's app shows it for each night. Time spent lying awake in bed doesn't count toward your goal.

Why can't my sleep debt go below zero?

Sleeping longer than your goal pays back debt you already have, but it doesn't store extra sleep for later nights.