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Optymalny sen składa się z 90-minutowych cykli. Oblicz, kiedy się obudzić — lub kiedy się położyć.
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Computes optimal wake-up or bedtimes based on 90-minute sleep cycles.
One sleep cycle lasts about 90 minutes and consists of 4 phases: N1 (falling asleep), N2 (light sleep), N3 (deep sleep) and REM (dreaming). Waking during N3 or REM causes "sleep inertia" — grogginess lasting 30–60 minutes.
| Cycles | Sleep time | Assessment |
|---|---|---|
| 4 cycles | 6 hours | Minimum |
| 5 cycles | 7.5 hours | Optimal |
| 6 cycles | 9 hours | Ideal |
How many hours does an adult need? CDC recommends 7–9 hours for adults (18–60 years). Teenagers need 8–10 hours, older adults 7–8 hours.
Are naps healthy? A 20–30 minute power nap improves concentration without entering deep sleep. A longer nap may make it harder to fall asleep at night.
Sleep progresses through repeated cycles of ~90 minutes, each with non-REM stages (light, light, deep slow-wave) and one REM stage. Deep sleep drives physical restoration and growth hormone release. REM sleep consolidates memory and regulates emotion. Waking mid-cycle causes "sleep inertia" — grogginess lasting 20–30 minutes.
| Age group | Recommended hours |
|---|---|
| Teenagers (14–17) | 8–10 hours |
| Young adults (18–25) | 7–9 hours |
| Adults (26–64) | 7–9 hours |
| Older adults (65+) | 7–8 hours |
Sleep deprivation increases ghrelin (hunger hormone) and decreases leptin (satiety hormone), leading to increased appetite — especially for high-calorie foods. Less than 6 hours/night is associated with significantly higher obesity risk.