Sleep Calculator

Find the ideal bedtime to wake up between full sleep cycles.

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⚠️ This calculator is for guidance only. It does not replace medical diagnosis or advice from a healthcare professional.

The sleep calculator tells you when to go to bed so that you wake up after completing full 90-minute sleep cycles. Waking at the end of a cycle reduces grogginess and tiredness. Enter your desired wake-up time and age to get several bedtime options based on the number of cycles you want to complete. Use it as many times as you need: it is completely free, requires no sign-up and works directly in your browser.

Frequently asked questions

¿Cuánto dura un ciclo de sueño?
Un ciclo completo de sueño dura unos 90 minutos e incluye sueño ligero, profundo y REM. Completar ciclos enteros ayuda a despertar con menos somnolencia.
¿Por qué me despierto cansado aunque duerma mucho?
A menudo es porque te despiertas a mitad de un ciclo de sueño. Acostarte para completar ciclos completos, y mantener un horario regular, reduce el aturdimiento matinal.
How long does a sleep cycle last?
A full sleep cycle lasts about 90 minutes and includes light, deep and REM sleep. Completing full cycles helps you wake up with less drowsiness.
Why do I wake up tired even after sleeping a lot?
Often it is because you wake up mid sleep cycle. Going to bed to complete full cycles, and keeping a regular schedule, reduces morning grogginess.

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