ideal bedtime & wake time · based on sleep cycles (commonly ~90 min each)
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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.
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Frequently asked questions
Enter your wake-up time and this calculator works backward in sleep cycles (commonly around 90 minutes each) to suggest bedtimes that align with a natural wake point, rather than an odd point mid-cycle. We also build in about 15 minutes for the time it typically takes to actually fall asleep, so the suggested bedtimes reflect a realistic total.
Most healthy adults do well with 5–6 full sleep cycles per night — roughly 7.5 to 9 hours — which this calculator highlights as "Recommended."
Sleep cycles move through light sleep, deep sleep, and REM. Waking during deep sleep tends to feel jarring, while waking near the end of a cycle (lighter sleep) tends to feel more natural.
It varies — teens generally need 8–10 hours, most adults need 7–9 hours, and older adults often do well with 7–8 hours, as shown in the age-based table above.
No — this is a planning tool based on average cycle length, not a measurement of your actual sleep. A wearable can show your real sleep stages; this helps you plan bedtimes in advance.
Yes — enter the time you went to bed and woke up in the "Log last night's sleep" section, and it's saved privately in your browser. You'll see your duration for each of the last 7 nights and a running average.
Nights of at least 7 hours are highlighted in the weekly chart, since 7-9 hours is the generally recommended range for most adults. It's a simple visual cue, not a medical threshold.
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.