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Sleep Time Calculator
Best bedtimes based on sleep cycles
Best Bedtimes
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💡 Sleep Science: Each sleep cycle = ~90 minutes. Best sleep = 5 or 6 complete cycles.
What is a Sleep Calculator?
Calculates optimal bedtime or wake time based on 90-minute sleep cycles - ensuring you wake refreshed at the end of a complete cycle.
How It Works
Sleep occurs in 90-minute cycles. A full night = 4-6 complete cycles (6-9 hours). Calculator adds average 14-minute sleep onset time.
Example
Bedtime 11:00 PM - sleep onset 11:14 PM - Optimal wakes: 4:44 AM (4 cycles), 6:14 AM (5 cycles), 7:44 AM (6 cycles - ideal for most adults).
Pro Tips
- Adults need 7-9 hours (4-6 cycles). Chronic under-sleep increases diabetes and heart disease risk.
- Consistent sleep-wake schedule matters more than total hours - irregular schedules disrupt circadian rhythm.
- Avoid screens 1 hour before bed - blue light suppresses melatonin production by up to 50%.
- Room temperature 18-20C promotes deeper sleep by facilitating core body temperature drop.
FAQ
How many sleep hours?▼
Adults: 7-9 hours. Teens: 8-10 hours. School-age children: 9-11 hours.
What is REM sleep?▼
Rapid Eye Movement sleep: the dreaming stage crucial for memory consolidation and emotional processing.
How to tell if sleep deprived?▼
Falling asleep in under 5 minutes, needing an alarm, daytime drowsiness indicate chronic sleep deprivation.
Does napping compensate for lost sleep?▼
A 20-30 min nap reduces sleepiness but cannot fully replace lost night sleep over time.