Frequently asked questions
General
How many hours of sleep do adults need?
7 to 9 hours. What matters most is complete cycles — typically 4 to 6 cycles of 90 minutes.
Does this replace a doctor?
No. For chronic insomnia, sleep apnea, or excessive daytime sleepiness, see a sleep specialist.
Can I share my results?
Yes — the Share button copies a URL with your time, latency, and cycle settings.
What is the best time to wake up?
It depends on your bedtime and cycle length. Use our calculator — the highest energy score marks the best slot.
How does CycleZen make money?
Through non-intrusive Google AdSense ads, only after you consent to marketing cookies. The tools remain free.
Sleep cycles
What are the 4 stages of sleep?
N1 (light), N2 (lighter), N3 (deep), and REM. A full cycle runs through these in ~90 minutes.
Can I sleep 6 hours and feel rested?
Yes if you complete 4 full cycles (6h sleep + latency). Quality matters as much as duration.
Calculators
Which calculator should I use?
Bedtime calculator if you know your alarm time. Wake-up calculator if you are going to bed now. Power nap for afternoon naps.
Are results medically accurate?
They are estimates based on average cycle length. Individual variation is 80–120 minutes per cycle.
Naps
How long should a power nap be?
20–26 minutes avoids deep sleep. A full 90-minute nap completes one cycle.
Will a nap ruin my night sleep?
Short naps before 3 PM rarely do. Long naps after 4 PM can delay nighttime sleep.