A sleep calculator finds the ideal bedtime or wake time using 90-minute sleep cycles. Waking at the end of a cycle leaves you more refreshed than waking mid-cycle.
A sleep calculator finds the ideal bedtime or wake time using 90-minute sleep cycles. Waking at the end of a cycle leaves you more refreshed than waking mid-cycle. Our sleep calculator is built on the same core sleep cycle calculator when should i go to bed best time to wake up and is trusted by students, professionals and everyday users who need a fast, accurate result. Because every calculation runs locally in your browser, there is no waiting, no sign-up and no limit on how often you use it.
The 90-Minute Circadian Sleep Cycle
Human sleep progresses through distinct 90-minute cycles of light sleep, deep slow-wave sleep, and REM dreaming.
Waking Up Refreshed Between Cycles
Waking in the middle of a deep sleep cycle causes sleep inertia and grogginess. Waking at the end of a 90-minute cycle ensures alertness.
Factoring in Fall-Asleep Time (Sleep Latency)
The average adult takes 14 minutes to drift off to sleep. Our calculator automatically builds this latency into recommended bedtimes.
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