Sleep Calculator
Wake up refreshed by timing sleep to 90-minute cycles.
How it works
NREM 1
5–10 min
5–10 min
NREM 2
20 min
20 min
NREM 3
Deep
Deep
REM
Dream
Dream
One sleep cycle lasts approximately 90 minutes. Waking up in the middle of a cycle leaves you groggy. Timing your wake-up to cycle boundaries means you wake in light sleep — naturally refreshed.
The calculator adds 14 minutes for average sleep onset time.