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Когда проснуться, чтобы чувствовать себя хорошо?
Sleep occurs in cycles of roughly 90 minutes, alternating between light sleep, deep sleep, and REM sleep. Waking up at the end of a complete cycle, rather than in the middle of one, generally feels less groggy.
How it's calculated
This calculator adds about 15 minutes to fall asleep, then works forward or backward in increments of 90 minutes (one full sleep cycle) to suggest optimal bedtimes or wake times.
Example
If you plan to wake up at 7:00 AM, going to bed around 11:15 PM allows for five complete 90-minute sleep cycles (7.5 hours of sleep).
Часто задаваемые вопросы
Is 90 minutes exactly how long a sleep cycle lasts?
It’s an average. Actual sleep cycle length varies by individual and can range from about 70 to 120 minutes, and also shifts across the night.
How many cycles should I aim for?
Most adults benefit from 5 to 6 full cycles per night, roughly corresponding to 7.5 to 9 hours of sleep.
Why does waking mid-cycle feel worse?
Waking during deep sleep can cause sleep inertia — grogginess and reduced alertness — because the brain hasn't completed its natural transition to a lighter sleep stage.