Sleep Calculator

I want to wake up at
+ 14 min average time to fall asleep
Suggested bedtimes (complete sleep cycles)
💤 Each sleep cycle is ~90 minutes. Waking up at the end of a cycle helps you feel more rested.
I need to wake up at
Enter your required wake time
Go to bed at these times to get complete sleep cycles
⏰ Adults need 7–9 hours (5–6 cycles). Teenagers need 8–10 hours. Children need 9–11 hours.
I'm falling asleep now at
Nap durations — wake up at these times
😴 Power nap (10–20 min) boosts alertness. 90-min nap completes a full cycle. Avoid napping after 3pm.
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Sleep Cycles
A sleep cycle lasts ~90 minutes and includes light sleep, deep sleep (slow wave), and REM sleep. Completing full cycles leaves you more refreshed.
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Sleep Stages
N1 Light sleep (5%)
N2 Core sleep (45%)
N3 Deep sleep (25%)
REM Dream sleep (25%)
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Recommended Hours
Newborns (0-3m)14–17h
Infants (4-11m)12–15h
Toddlers (1-2y)11–14h
Preschool (3-5y)10–13h
School age (6-13y)9–11h
Teens (14-17y)8–10h
Adults (18-64y)7–9h
Seniors (65+y)7–8h
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Sleep Tips
  • Keep a consistent sleep schedule, even on weekends
  • Avoid screens 1h before bed (blue light disrupts melatonin)
  • Keep bedroom cool (65–68°F / 18–20°C)
  • Avoid caffeine after 2pm
  • Exercise regularly but not within 3h of bedtime

How to Use the Sleep Calculator

  1. Choose a mode: "I want to wake up at..." to find your ideal bedtime, or "I want to go to bed at..." to find optimal wake times.
  2. Enter your target wake time or bedtime.
  3. The calculator shows 4-6 optimal sleep times based on 90-minute sleep cycles.
  4. Use the Nap Planner for daytime nap options from a 10-minute power nap to a full 90-minute cycle.

Why Sleep Cycles Matter

Sleep is not uniform — it occurs in 90-minute cycles, each containing light sleep, deep sleep (slow-wave), and REM sleep stages. Waking up at the wrong point in a cycle — typically during deep sleep — causes "sleep inertia": the groggy, disoriented feeling that persists for an hour or more even after a full night's sleep. Waking at the end of a complete cycle, during the light sleep phase, leaves you feeling alert and refreshed.

The calculator adds 14 minutes to your bedtime to account for the average time to fall asleep (sleep onset latency). This means if you need to wake at 7:00 AM and want 5 cycles (7.5 hours of sleep), your ideal bedtime is 11:16 PM — not 11:30 PM. These small adjustments add up to dramatically better mornings over time.

Frequently Asked Questions