Find the ideal times to wake up or fall asleep based on 90-minute sleep cycles. Wake up refreshed — not mid-cycle groggy.
Your Sleep Plan
Choose to calculate wake time or sleep time
Best Sleep Times
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— for 6 sleep cycles (9h)
Cycles
Duration
Time
Set your wake or sleep time
Each sleep cycle is ~90 minutes. Waking at the end of a cycle means you feel more refreshed.
Sleep by Age — Recommended Hours
Age Group
Hours/night
Newborn (0–3 months)
14–17 hours
School age (6–12)
9–11 hours
Teenager (13–18)
8–10 hours
Adult (18–64)
7–9 hours
Older adult (65+)
7–8 hours
Frequently Asked Questions
What is a sleep cycle?
A sleep cycle is approximately 90 minutes long and includes light sleep, deep sleep, and REM sleep stages. Most adults need 5–6 complete cycles (7.5–9 hours) per night.
Why do I wake up tired even after 8 hours?
Waking up in the middle of deep sleep (NREM stage 3) leaves you feeling groggy — called sleep inertia. This calculator helps you time your alarm to the end of a cycle instead.
How accurate is the 90-minute cycle estimate?
Individual cycles vary between 80–110 minutes. The 90-minute figure is an average. The 14-minute fall-asleep time is also the average for adults — adjust based on how quickly you typically fall asleep.