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Sleep Science

Sleep Calculator

Wake up refreshed, not groggy. Find your perfect bedtime or wake-up time based on natural 90-minute sleep cycles.

How it works: Sleep happens in 90-minute cycles of Light Sleep, Deep Sleep and REM. Waking at the end of a cycle โ€” not in the middle โ€” means you feel alert and refreshed. This calculator times your sleep to hit cycle ends perfectly.
What time do you want to wake up?
06
:
30
โฑ Time to fall asleep:
Recommended Sleep Times
Based on 90-minute sleep cycles
โœฆ One 90-Minute Sleep Cycle
Light
Deep
REM
Light Sleep (20 min)
Deep Sleep (30 min)
REM Sleep (40 min)
โœฆ Sleep Better Tonight
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Stop screens 30โ€“60 minutes before bed. Blue light suppresses melatonin production and delays the onset of sleep by up to an hour.
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Keep your room cool. Core body temperature naturally drops as you fall asleep. A cool room accelerates this.
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Get natural light in the morning. Morning sunlight resets your circadian clock and makes it easier to fall asleep at the right time that night.
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Avoid caffeine after 2pm. Caffeine has a half-life of 5โ€“6 hours. A 3pm coffee can still be half-strength in your system at 8pm.
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Keep a consistent sleep schedule. Going to bed and waking at the same time every day โ€” including weekends โ€” is the single most powerful sleep habit.
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Wind down intentionally. Create a 20-minute pre-sleep ritual โ€” dimmed lights, gentle stretching or reading โ€” to signal to your brain that sleep is coming.