Sleep Calculator

Find the best time to sleep or wake up

I Need to Wake Up At

Sleep Cycle Tip

Each sleep cycle is ~90 minutes. Waking between cycles helps you feel more refreshed.

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Sleep Calculator – Optimize Sleep Cycles

Our Sleep Calculator helps you wake up feeling refreshed by timing your sleep with 90-minute sleep cycles.

How Sleep Cycles Work

Each sleep cycle is approximately 90 minutes. Waking during light sleep (between cycles) helps you feel more refreshed.

  • 4 cycles = 6 hours (minimum)
  • 5 cycles = 7.5 hours (good)
  • 6 cycles = 9 hours (optimal)

Frequently Asked Questions

Why do I feel groggy after 8 hours?

8 hours isn't a complete cycle (7.5 or 9 hours would be). You might wake mid-cycle, causing grogginess.