Why you can’t sleep the night before
If you slept 2 a.m. to 10 a.m. all holiday, your body clock is now hours later than usual. It is the social jet lag of a weekend, stretched over days. Going by the CDC’s jet lag guidance, the body clock moves only about 1 to 1.5 hours a day, so a three-hour shift won’t undo itself overnight.
A reset plan
| Day | Wake | Bedtime target (5 cycles, 15 min to fall asleep) |
|---|---|---|
| 3 days before | 09:00 | 01:15 |
| 2 days before | 08:00 | 00:15 |
| Night before | 07:00 | 23:15 |
| First day back | 07:00 | 23:15 |
- Move wake-up earlier first, and get bright light as soon as you are up.
- If you nap, keep it short and avoid late afternoon.
- If you can’t sleep, don’t lie there; get up for a bit and try again.
The clock change
In 2026 clocks go back one hour on Sunday, November 1 in the US and on October 25 in the UK and the EU. If you keep your usual wake time by the clock, you are getting up an hour later by your body clock that first week, and evenings feel longer. Treat it like a small one-hour trip west and keep your wake-up time steady for a few days.
Checking it in the app
Enter each day’s wake time
In Sleep Calculator’s When to sleep?, enter that day’s wake-up target to get the bedtime. Move the wake-up time a day at a time, as in the table, and recalculate.
Turn on the bedtime notification
In Settings, turn on Bedtime notification and set it about 30 minutes before your target bedtime so you have time to wind down. While your plan changes daily, update the reminder time too.
Watch your bedtime regularity score
Bedtime regularity in Stats scores 0–100 from how spread out the bedtimes of your last 14 records are (their standard deviation). A spread of 0 minutes scores 100; 2 hours scores 0. As holiday nights drop out and the score climbs, your rhythm is coming back.
FAQ
The Stats tab is locked.
Stats unlock for 24 hours after an optional rewarded ad, and need at least two records. Sleep debt and average sleep in the Log tab are free.
Can I reset in one day?
Pulling an all-nighter to reset leaves you drowsy and accident-prone the next day, so it isn’t recommended. About an hour a day is realistic.
Sleep Calculator
No sign-up, and your sleep log stays on your phone. Free on Android.