Sleep Calculator
Find your ideal bedtime or wake-up time using 90-minute sleep cycles. Based on CDC sleep recommendations for your age group.
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I need to wake up at...
Age Group
Recommended: 7–9 hours
Best Bedtime for 07:00 wake-up
9:45 PM
6 cycles · 9h sleep
All Options
9:45 PM
6 cycles · 9h
11:15 PM
5 cycles · 7.5h
12:45 AM
4 cycles · 6h
2:15 AM
3 cycles · 4.5h
⚡ Includes ~15 min to fall asleep
Sleep Stages (per 90-min cycle)
😴 Light Sleep (N1/N2)55%
Memory consolidation begins. Easy to wake. Makes up majority of the night.
💤 Deep Sleep (N3)25%
Physical repair, immune function, growth hormone release. Hardest to wake from.
🧠 REM Sleep20%
Dream stage. Emotional processing, creativity, learning consolidation.
Sleep Tips
- 💡Maintain a consistent sleep schedule — same bedtime and wake time, even on weekends.
- 💡Keep your bedroom cool (65–68°F / 18–20°C) — core body temperature must drop to initiate sleep.
- 💡Avoid screens 30–60 min before bed — blue light suppresses melatonin production by up to 50%.
- 💡Avoid caffeine after 2pm — its half-life is 5–7 hours, so an afternoon coffee is half-strength at 9pm.
- 💡A 20-minute nap (before 3pm) improves alertness without disrupting nighttime sleep.
- 💡Waking mid-cycle (incomplete REM) causes grogginess — align your alarm with a full cycle.
- 💡Exercise improves sleep quality, but intense workouts within 2–3 hours of bedtime can delay sleep.