Sleep guides

In-depth, science-backed guides to help you understand how sleep works and how to get more out of every night. Start with sleep cycles, then dig into the topic you need.

• Sleep cycles explained — the four stages of sleep (N1, N2, N3, REM) and how the 90-minute cycle works
• How much sleep you need by age — a full chart from newborns to seniors and why your needs change
• How to fall asleep faster — 12 science-backed methods, from the military technique to 4-7-8 breathing
• The complete power nap guide — how long to nap, when, and the coffee-nap trick
• Sleep debt — what it is, what it does to you, and how to actually recover lost sleep

Ready to plan tonight?

Use the sleep cycle calculator to turn your wake-up time into the best bedtimes, or browse our free sleep tools for naps, sleep debt, chronotype, and caffeine.