ideal bedtime & wake time · based on 90-minute sleep cycles
Plan around
Sleep Facts
Recommended sleep by age
Age group
Recommended
Teens (14–17)
8–10 hrs
Young adults (18–25)
7–9 hrs
Adults (26–64)
7–9 hrs
Older adults (65+)
7–8 hrs
Sleep isn't uniform through the night — it moves through light sleep, deep sleep, and REM in a repeating pattern that commonly runs about 90 minutes per cycle. Waking up in the middle of deep sleep tends to feel groggy, while waking near the end of a cycle, as it shifts back toward lighter sleep, tends to feel more refreshed. That's why these calculators work in full-cycle increments rather than picking an exact hour count.
Figures are based on commonly cited sleep-cycle length and general guidelines from sleep research — individual cycle length and needs vary. This isn't medical advice; if you have ongoing sleep difficulties, talk to a doctor.