BEHIND THE BEDTIMES
A useful estimate.
A calmer starting point.
Snoozely is a free sleep planning tool for adults. It helps you work backward from a wake-up time or forward from a bedtime. It cannot measure your sleep or promise that an alarm will ring between sleep stages.
How we calculate
Bedtime = chosen wake-up time − estimated sleep duration − time to fall asleep. Wake-up time = chosen bedtime + time to fall asleep + estimated sleep duration.
Nighttime options use four, five and six estimated cycles. The default cycle length is 90 minutes; you can adjust it from 80 to 100 minutes. The default 15-minute fall-asleep allowance is a convenient assumption, not a measurement or a universal average.
We label the five-cycle option as a starting point only when its estimated sleep duration falls between 7 and 9 hours. An option under 7 hours is marked “Short sleep.” A cycle count alone does not tell you whether you are getting enough sleep.
Dates and daylight saving
Chosen times use their next occurrence in your device’s local time zone. Sleep durations are elapsed minutes, so clock times can differ on nights when daylight saving changes. A bedtime before the current moment is marked “Already passed.” Sleep now and nap modes recalculate from the current time each time you press the button.
Nap planning
Nap mode offers 20-minute and 30-minute sleep durations, plus one longer estimated cycle, with your fall-asleep allowance added. The shorter nap is a planning option, not a promise about sleep stages. Longer naps may cause grogginess or interfere with nighttime sleep.
Sources and limits
- NHLBI: How much sleep is enough? — adult sleep duration.
- NHLBI: Sleep phases and stages — sleep cycles and their variability.
- NHLBI: Healthy sleep habits — routines and nap guidance.
Content reviewed October 4, 2026. Snoozely is not a medical device and does not offer diagnosis or treatment. If sleep problems persist or daytime sleepiness affects your life, consult a healthcare professional.