Sleep Calculator

Calculate optimal sleep and wake times based on 90-minute sleep cycles with step-by-step solutions.

Your Input

I want to go to bed at...

:

Choose a mode, enter your bedtime or wake time (or use Sleep Now), then click Calculate to see optimal times based on 90-minute sleep cycles.

Complete User Guide

What is a Sleep Cycle?

A complete sleep cycle lasts about 90 minutes and includes light sleep, deep sleep, and REM (dream) sleep. Waking at the end of a cycle helps you feel refreshed.

Calculation Modes

When to Wake Up

Enter bedtime, get optimal wake times for 4–6 cycles.

When to Go to Bed

Enter wake time, get recommended bed times.

Sleep Now

Get wake times if you go to sleep right now.

How to Use This Calculator

  1. Select a tab: When to Wake Up, When to Go to Bed, or Sleep Now.
  2. Enter your bedtime or wake time (or use Sleep Now).
  3. Click the calculate button to get optimal times.
  4. Choose the option that works best for you from the results.
  5. Click Reset to clear and start over.

Sleep Cycle Stages

Stage 1: Light sleep (1-5 min)

Stage 2: Light sleep (10-25 min)

Stage 3: Deep sleep (20-40 min)

REM: Dream sleep (10-60 min)

Recommended Sleep

Adults: 7-9 hours (5-6 cycles)

Teens: 8-10 hours (5-7 cycles)

Children: 9-12 hours

Seniors: 7-8 hours

Important Notes

  • Average time to fall asleep: 15 minutes; each cycle is approximately 90 minutes.
  • Waking between cycles causes grogginess; waking at cycle end helps you feel refreshed.
  • Individual sleep needs may vary; consistency is key for quality sleep.

Common Applications

  • Planning sleep schedule
  • Setting alarms
  • Improving sleep quality
  • Reducing morning grogginess
  • Jet lag recovery

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