๐ด Sleep Cycle Calculator
Suggested Wake Times
Calculated using 90-minute sleep cycles plus about 14 minutes to fall asleep.
Based on the idea that sleep cycles in roughly 90-minute stages, this tool suggests optimal bedtimes or wake times โ a rough guide for waking up feeling less groggy. Handy when you need to work backward from tomorrow's schedule to decide what time to go to bed.
How to use
- Choose "From Bedtime" or "From Wake Time" mode.
- Enter the time you plan to go to bed, or the time you want to wake up.
- See suggested wake times (or bedtimes) spaced 90 minutes apart.
FAQ
Where does the 90-minute figure come from?
Sleep generally alternates between non-REM and REM stages in roughly 90-minute cycles, and waking near the boundary between cycles is thought to feel less groggy โ though this varies by person.
Can I work backward from a target wake-up time?
Yes โ enter your desired wake time and it suggests bedtime candidates spaced 90 minutes apart.
Does it account for the time it takes to fall asleep?
Yes โ it adds a typical 14-minute allowance for falling asleep before calculating the 90-minute cycles.
Does it work for shift work or an irregular schedule?
Yes โ you can calculate from either a bedtime or a wake time regardless of what time of day it is.
Does this guarantee I'll fix my sleep deprivation?
No. It's just a guide based on cycle boundaries โ actual sleep quality and the amount of sleep you need vary by person, so make sure you're also getting enough total sleep.