Bedtime Calculator
To wake up at your alarm refreshed, you should be in bed by:
6 cycles · 9.0h
09:45 PM
5 cycles · 7.5h
11:15 PM
4 cycles · 6.0h
12:45 AM
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Frequently asked questions
What time should I go to bed?+
Subtract 7.5 to 9 hours of sleep + your fall-asleep time from your wake-up alarm. This calculator does it instantly.
Why are my bedtime and wake-up time more important than total hours?+
Consistency stabilizes circadian rhythm. A consistent 7-hour schedule often beats a variable 8-hour schedule for energy and mood.
Is 10 PM really the magic bedtime?+
Not universally — chronotype matters. Night owls sleeping at 10 PM often lie awake. Aim for the bedtime that gives you full cycles before your needed wake time.
How many hours of sleep do adults really need?+
Most adults need 7–9 hours; teens 8–10; older adults 7–8. Genetic 'short sleepers' (<5% of people) thrive on 6, but most people who think they're short sleepers are simply sleep-deprived.
Does eating late push my bedtime later?+
Yes — heavy meals within 3 hours of bed raise core body temperature and delay melatonin onset, pushing your natural sleep window 30–60 minutes later.
How long should it take to fall asleep?+
10–20 minutes is normal. Under 5 minutes signals sleep deprivation; over 30 minutes regularly suggests insomnia or a misaligned circadian phase.
Can I use this calculator for kids?+
The 90-minute cycle math works, but children need more total sleep — 9–11 hours school-age, 10–13 hours preschool — so add cycles accordingly.
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