Sleep Calculator
Find the best time to wake up or go to bed based on 90-minute sleep cycles. Wake up refreshed every time.
I plan to go to bed at...
Wake up at...
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
Recommended Sleep by Age (NSF Guidelines)
| 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 |
Sleep Calculator
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.
How Sleep Cycles Work
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 15-Minute Buffer
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.
Tips for Better Sleep
- Keep a consistent sleep schedule — even on weekends.
- Avoid screens 1 hour before bed (blue light suppresses melatonin).
- Keep your bedroom cool, dark, and quiet.
- Avoid caffeine after 2 PM.
- Exercise regularly, but not too close to bedtime.