Sleep Cycle Calculator
Find the best time to wake up or go to sleep based on 90-minute sleep cycles to wake up refreshed
09:46 PM
11:16 PM
12:46 AM
02:16 AM
03:46 AM
05:16 AM
A full sleep cycle lasts about 90 minutes and includes light sleep, deep sleep, and REM stages. Waking up at the end of a cycle (instead of mid-cycle) helps you feel more refreshed. Most adults need 4–6 complete cycles per night.
Sleep Calculator — Wake Up Refreshed
Find the ideal bedtime or wake-up time based on 90-minute sleep cycles. Waking up at the end of a cycle (rather than mid-cycle) leaves you feeling more rested.
FAQ
What is a sleep cycle?
A sleep cycle is approximately 90 minutes long and includes light sleep, deep sleep (NREM), and REM sleep. Most adults complete 4–6 cycles per night.
How much sleep do I need?
Adults: 7–9 hours (4–6 cycles). Teenagers: 8–10 hours. School-age children: 9–11 hours. These are guidelines — individual needs vary.
Why do I feel tired even after 8 hours?
You may be waking up in the middle of a deep sleep cycle. Try adjusting your alarm to the nearest 90-minute boundary, or use a sleep tracking app.
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