Science-backed sleep recommendations by age group, sleep cycle breakdown, and your personal bedtime calculator.
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Recommended for you
7–9 hrs
Adult (18–64 years)
Consistently sleeping within this range is associated with optimal cognitive performance, metabolic health, and immune function.
If you wake at —
Go to bed by
—
Sleep Recommendations by Age Group
| Age Group | Recommended Hours | May Be Appropriate | Not Recommended | Quality Priority |
|---|
Sleep Architecture — What Happens Each Night
Deep Sleep
~20%
Physical repair, immune function, growth hormone release
REM Sleep
~25%
Memory consolidation, emotional regulation, dreaming
Light Sleep
~50%
Transitional stage; muscle relaxation, easy to wake
Awakenings
~5%
Brief arousals between cycles; normal and expected
One complete sleep cycle lasts approximately 90 minutes. A full night's sleep contains 4–6 cycles. Waking at the end of a cycle (rather than mid-cycle) helps you feel more refreshed.
Bedtime Calculator
Enter your wake-up time and we'll calculate ideal bedtimes based on 90-minute sleep cycles (plus ~14 min to fall asleep).
Sleep Hygiene — Evidence-Based Tips
Keep your room cool
Optimal sleep temperature is 16–19°C (60–67°F). Core body temperature drops at sleep onset.
Limit screens before bed
Blue light from devices suppresses melatonin. Stop screen use 60–90 min before sleep.
Cut caffeine after 2 PM
Caffeine has a 5–6 hour half-life and can disrupt sleep quality even when you fall asleep easily.
Maintain consistent timing
Waking at the same time daily — even weekends — anchors your circadian rhythm powerfully.
Wind-down routine
A 30–60 min pre-sleep ritual signals the brain to transition toward sleep. Reading, stretching, or meditation all help.
Morning light exposure
10–30 min of bright light within an hour of waking sets your circadian clock for the day.
