Find the best time to wake up or go to bed based on 90-minute sleep cycles. Wake up refreshed every time.
5:15 AM
4 cycles · 6 hours — Minimum recommended
6:45 AM
5 cycles · 7.5 hours — Recommended
8:15 AM
6 cycles · 9 hours — Optimal rest
| Age Group | Recommended Sleep |
|---|---|
| Newborn (0–3 months) | 14–17 hours |
| Infant (4–11 months) | 12–15 hours |
| Toddler (1–2 years) | 11–14 hours |
| Preschool (3–5 years) | 10–13 hours |
| School Age (6–13 years) | 9–11 hours |
| Teen (14–17 years) | 8–10 hours |
| Young Adult (18–25 years) | 7–9 hours |
| Adult (26–64 years) | 7–9 hours |
| Older Adult (65+) | 7–8 hours |
Our Sleep Calculator helps you figure out the best time to wake up or go to bed based on your body's natural 90-minute sleep cycles. Waking up between cycles — rather than in the middle of one — helps you feel more refreshed and alert.
A typical night's sleep consists of multiple 90-minute cycles, each containing light sleep, deep sleep, and REM (rapid eye movement) sleep. Most adults need 5–6 complete cycles (7.5–9 hours) for optimal rest. Waking mid-cycle can cause sleep inertia — that groggy, disoriented feeling.
The calculator adds 15 minutes to account for the average time it takes to fall asleep. If you tend to fall asleep faster or slower, adjust your bedtime accordingly.