Bedtime calculator
This calculator needs JavaScript. The quick-reference table below works without it, and the formula is just above it.
How it works
Count back from your wake-up time: first the sleep you need, then the time it usually takes you to fall asleep. That's your bedtime. Wind-down starts a little earlier: lights lower, screens away, the same routine each night. Not sure how much sleep you need? Try the sleep need estimator.
The 90-minute option counts back whole sleep cycles instead. It's a rule of thumb: real cycles run from about 70 to 120 minutes and change through the night, so treat it as a guide to waking at a lighter moment, not a promise.
bedtime = wake time − sleep need − time to fall asleep
wind-down = bedtime − wind-down length
cycle bedtimes = wake time − (6, 5 or 4 × 90 min) − time to fall asleep
Quick reference
| Wake at | Need 7 h | Need 7 h 30 min | Need 8 h | Need 9 h |
|---|---|---|---|---|
| 5:30 AM | 10:15 PM | 9:45 PM | 9:15 PM | 8:15 PM |
| 6:00 AM | 10:45 PM | 10:15 PM | 9:45 PM | 8:45 PM |
| 6:30 AM | 11:15 PM | 10:45 PM | 10:15 PM | 9:15 PM |
| 7:00 AM | 11:45 PM | 11:15 PM | 10:45 PM | 9:45 PM |
| 7:30 AM | 12:15 AM | 11:45 PM | 11:15 PM | 10:15 PM |
| 8:00 AM | 12:45 AM | 12:15 AM | 11:45 PM | 10:45 PM |
How Auralo does this
Auralo doesn't make you guess your sleep need. It learns it from the nights after which your heart-rate variability was at or above your usual, adds time after a hard day, and pays back part of any sleep debt. Then it sets tonight's wind-down and bedtime, sends one notification with both times, and the smart alarm on your Watch wakes you in light sleep within 30 minutes of your wake time.
Questions
How much sleep do I need?
Most adults need 7 to 9 hours. The right amount for you is the one after which you wake without a fight and stay alert through the afternoon. The sleep need estimator gives a starting point.
Should I use 90-minute cycles?
Use them as a rough guide. Cycles vary from about 70 to 120 minutes, so a cycle-based bedtime won't land you exactly at the end of one. Getting enough total sleep matters more.
What if I can't fall asleep at my new bedtime?
Move bedtime earlier by 15 minutes every few nights rather than all at once, and keep your wake time fixed, weekends included.
Is this medical advice?
No. It's wellness information. If you sleep badly most nights, talk to a doctor.
Sources
- Watson NF et al. Recommended amount of sleep for a healthy adult: AASM and SRS joint consensus statement. Sleep 2015;38(6):843–844.
- Carskadon MA, Dement WC. Normal human sleep: an overview. In Principles and Practice of Sleep Medicine. Elsevier.
Wellness information, not medical advice. If you have a health condition, follow your clinician's guidance.