Sleep calculator / Planning guides
What time should I go to bed to wake up at 6 AM?
A 6 AM alarm leaves little room to catch up in the morning. For eight hours of sleep and a 15-minute fall-asleep allowance, plan to get into bed at 9:45 PM the night before.
Bedtimes 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 | Get into bed | Day |
|---|---|---|
| 7 hours | 10:45 PM | Previous evening |
| 8 hours | 9:45 PM | Previous evening |
| 9 hours | 8:45 PM | Previous evening |
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.
- 8:45 PM — 9 hours of sleep, about 6 estimated cycles
- 10:15 PM — 7.5 hours of sleep, about 5 estimated cycles
- 11:45 PM — 6 hours of sleep, about 4 estimated cycles (Short sleep)
Make this schedule practical
Work backward from your morning commitments. If you leave home early, prepare breakfast, clothes and your bag before your wind-down. Moving a midnight bedtime directly to 9:45 PM may be hard to maintain; shift your evening schedule gradually and judge it by how you feel during the day.
Check the time you actually have
Getting into bed at 11 PM and taking 15 minutes to fall asleep leaves only 6 hours 45 minutes before a 6 AM alarm. A neatly timed cycle estimate does not make that duration adequate.
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.