Sleep calculator / Planning guides
If I go to bed at 10 PM, what time should I wake up?
Getting into bed at 10 PM and taking 15 minutes to fall asleep gives an eight-hour wake-up time of 6:15 AM. If you mean already asleep at 10 PM, that becomes 6 AM.
Wake-up times by sleep duration
These examples use 15 minutes to fall asleep. The duration column counts sleep, not time in bed. Most adults need 7–9 hours; choose a target that fits your needs.
| Sleep target | Wake up | Day |
|---|---|---|
| 7 hours | 5:15 AM | Following morning |
| 8 hours | 6:15 AM | Following morning |
| 9 hours | 7:15 AM | Following morning |
Compare estimated cycle options
The calculator uses a 90-minute cycle estimate. It cannot predict when your actual sleep stages end. The six-hour option is shown for comparison and is shorter than the usual adult recommendation.
- 7:15 AM — 9 hours of sleep, about 6 estimated cycles
- 5:45 AM — 7.5 hours of sleep, about 5 estimated cycles
- 4:15 AM — 6 hours of sleep, about 4 estimated cycles (Short sleep)
Make this schedule practical
A 10 PM bedtime can support an early morning, provided your evening routine makes it achievable. Finish preparations before you get into bed. If your alarm must ring at 6 AM, consider a 9:45 PM bedtime for an eight-hour sleep target rather than squeezing the fall-asleep allowance out of your rest.
Check the time you actually have
A fixed 6 AM alarm after a 10 PM bedtime provides an eight-hour window, but only 7 hours 45 minutes of estimated sleep with a 15-minute allowance. For nine hours of sleep from this bedtime, the wake-up time is 7:15 AM.
What if I take longer to fall asleep?
Change the fall-asleep allowance in the calculator. If you need 30 minutes instead of 15, move a suggested bedtime 15 minutes earlier or a suggested wake-up time 15 minutes later. Nighttime awakenings can reduce actual sleep further. Allow extra room when your own observations suggest you need it.
Should I wake at an exact cycle boundary?
Use the cycle options as estimates, not guarantees of feeling refreshed. Prioritize enough sleep and a schedule you can maintain. If a fixed alarm leaves too little time, change bedtime rather than deliberately cutting sleep to fit a cycle count.
Sources: NHLBI sleep duration guidance · Sleep stages.
Snoozely is a planning tool for adults. Set a separate alarm. If sleep problems or excessive daytime sleepiness persist, talk to a healthcare professional.