Sleep Calculator
Calculate optimal sleep times
Frequently Asked Questions
How does the Sleep Calculator determine optimal bedtime?
The calculator works backwards from your wake time using 90-minute sleep cycles. A full night is 5-6 cycles (7.5-9 hours). To wake at 7:00 AM, optimal bedtimes are 9:30 PM (6 cycles), 11:00 PM (5 cycles), or 12:30 AM (4 cycles).
What is a sleep cycle and why does it matter?
A sleep cycle lasts approximately 90 minutes and includes light sleep, deep sleep, and REM stages. Waking between cycles (rather than mid-cycle) helps you feel more refreshed. The calculator aligns your sleep with complete cycles.
How much sleep do I need by age?
Newborns: 14-17 hours. Toddlers: 11-14 hours. School age: 9-11 hours. Teenagers: 8-10 hours. Adults (18-64): 7-9 hours. Seniors (65+): 7-8 hours. Individual needs vary, but most adults need at least 7 hours.
How long does it take to fall asleep?
The average person takes 10-20 minutes to fall asleep (sleep latency). The calculator adds 14 minutes by default. If you consistently fall asleep in under 5 minutes, you may be sleep-deprived. Over 30 minutes may indicate insomnia.
What is the best time to wake up feeling refreshed?
Wake at the end of a complete sleep cycle, during light sleep. If you go to bed at 11:00 PM and fall asleep by 11:15 PM, optimal wake times are 4:45 AM (4 cycles), 6:15 AM (5 cycles), or 7:45 AM (6 cycles).