How Sleep Cycles Work
What actually happens while you sleep: the stages inside a cycle, why cycles average about 90 minutes, and why waking at a cycle end is an estimate, not a guarantee.
Sleep Guides
Short, honest guides about how sleep works and how to plan around it. No jargon, no miracle claims, and every number tied to a real source or a clearly labeled estimate. Start with whichever question is on your mind.
All guides
How Much Sleep Do You Need?
Age-based sleep recommendations from the National Sleep Foundation and the CDC, plus a practical way to find your own number. Sources reviewed October 2026.
How to Build a Consistent Sleep Schedule
A step-by-step approach: fix your wake time, build a wind-down routine, use light on purpose, and adjust realistically for shift work.
Why Do I Wake Up Tired After 8 Hours of Sleep?
Eight hours should be enough, so why are you exhausted? The real causes of unrefreshing sleep, from fragmented nights to mistimed alarms.
Why Do I Keep Waking Up at 3am?
Why the early morning hours break sleep so easily, what turns a brief awakening into an hour awake, and what to do at 3am tonight.
How to Fall Asleep Faster
Why trying harder backfires, plus a realistic wind-down routine, bedroom tweaks, and daytime habits that shorten the time to fall asleep.
Stages of Sleep: What Happens Each Night
N1, N2, N3, and REM: what each stage does, how the mix changes through the night, and why no device can track your stages precisely.
What Is the Best Sleep Position?
Back, side, or stomach? Honest guidance on positions for spinal alignment, snoring, and reflux, plus pillows that actually help.
How Long Should a Nap Be?
The two nap lengths that work, the groggy middle to avoid, the best time of day to nap, and how to nap without ruining tonight's sleep.
Put the guides to work
Every guide above connects to a free calculator you can use right away. No account, no sign-up.
These guides are educational. They are not medical advice. If you think you have a sleep disorder, talk to a qualified health professional. See how our calculations work for every assumption behind our tools.