How the calculator works
Your sleep doesn't happen in one continuous block. It's a series of 90-minute cycles, each containing phases of light sleep, deep slow-wave sleep, and REM. Waking up at the end of a cycle feels lighter and more refreshing than being jolted out of deep sleep mid-cycle.
This calculator adds a 14-minute buffer for the average time it takes to fall asleep, then counts back (or forward) in 90-minute increments. Five to six complete cycles per night = 7.5-9 hours of sleep, which is the range the research supports for most healthy adults.
How much sleep do you actually need?
| Age | Recommended cycles | Hours |
|---|---|---|
| Newborns (0-3 mo) | 10-12 cycles | 14-17 hrs |
| Toddlers (1-2 yr) | 7-9 cycles | 11-14 hrs |
| School age (6-13) | 6-8 cycles | 9-11 hrs |
| Teens (14-17) | 5-7 cycles | 8-10 hrs |
| Adults (18-64) | 5-6 cycles | 7-9 hrs |
| Older adults (65+) | 5-6 cycles | 7-8 hrs |
One thing the calculator can't fix
Getting the timing right means nothing if your sleep architecture is being shredded by nighttime mouth breathing. If you wake up with a dry throat, snore, or feel groggy despite "enough" hours — fix that first. The most impactful intervention for the majority of adults is keeping the mouth closed during sleep with a piece of skin-safe tape. Our brand comparison covers the options; the nasal-breathing pillar covers the physiology.
For the full optimization protocol, start with the complete sleepmaxxing guide.