Why 90 minutes?
A sleep cycle runs roughly 90 minutes through light, deep and REM stages. Waking at the seam between cycles is why 6 hours can beat 7.
Stop guessing when to sleep.
Step 1 of 3
Tap or drag anywhere on the ring to set your time.
Drag the handle to set your wake time
Glowing band is your night, the warm lead-in is wind-down, the amber dot is your last safe coffee, faint outer arcs are your sharpest hours.
Ideal bedtimes
Select one of these times to fall asleep at, so you wake at the end of a full 90-minute cycle.
Includes a 15-minute buffer for falling asleep. Waking between cycles — rather than mid deep-sleep — is what makes the difference between groggy and clear.
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Step 2
Find your chronotype
Set your time on the dial above to unlock this step.
The chronotype quiz opens as soon as you set a time.
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Step 3
Your results
Finish the quiz to see your sleep debt and share card.
Your Lion, Bear, Wolf or Dolphin card appears here — ready to screenshot.
How sleep timing works
Why chronotypes?
Dr. Michael Breus's Lion, Bear, Wolf and Dolphin framework describes when your body wants to sleep — not when your calendar demands it.
Why sleep debt?
Shortfalls accumulate. Thirty minutes a night is three and a half hours by Sunday, and it shows up as mood, focus and appetite.