Find the best time to wake up or go to sleep based on 90-minute sleep cycles. Avoid waking in deep sleep — wake up refreshed every time.
Adults need 7–9 hours per night. Teenagers need 8–10 hours. Children (6–12) need 9–11 hours. Newborns need 14–17 hours. Consistent sleep deprivation increases risk of obesity, diabetes, and heart disease.
A sleep cycle lasts approximately 90 minutes and includes light sleep (N1, N2), deep sleep (N3/slow-wave), and REM (dreaming) sleep. A full night typically consists of 5–6 complete cycles.
You likely woke up in the middle of a sleep cycle — during deep sleep or REM. Waking at the end of a complete 90-minute cycle leaves you feeling refreshed. This calculator helps you time your sleep to avoid mid-cycle waking.
Sleeping by 10–11 PM and waking at 6–7 AM aligns with natural circadian rhythms for most adults. However, the key is consistency and completing full 90-minute cycles. This calculator helps you find the exact times that work for your schedule.
Set a consistent wake-up time every day (including weekends). Avoid screens 1 hour before bed, limit caffeine after 2 PM, keep your room dark and cool (around 18°C), and use this calculator to plan your bedtime around complete sleep cycles.