Sleep calculator / Planning guides
If I go to bed at 12 AM, what time should I wake up?
12 AM means midnight. Getting into bed then and taking 15 minutes to fall asleep gives an eight-hour wake-up time of 8:15 AM. If you are already asleep at midnight, wake at 8 AM for eight hours.
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 | 7:15 AM | Following morning |
| 8 hours | 8:15 AM | Following morning |
| 9 hours | 9:15 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.
- 9:15 AM — 9 hours of sleep, about 6 estimated cycles
- 7:45 AM — 7.5 hours of sleep, about 5 estimated cycles
- 6:15 AM — 6 hours of sleep, about 4 estimated cycles (Short sleep)
Make this schedule practical
A midnight bedtime works best when your morning allows enough sleep. If you must wake at 6 or 7 AM, moving bedtime earlier creates more room for rest. Check AM and PM carefully when setting a separate alarm: 12 PM is noon, not midnight.
Check the time you actually have
Midnight to 7 AM is seven hours in bed and about 6 hours 45 minutes of sleep with a 15-minute allowance. Midnight to 9:15 AM allows nine hours of sleep with that same allowance.
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.