Sleep health guides · 60 articles
How Sleep Works
The science underneath sleep: stages, rhythms, REM, dreams, and the brain systems that shape rest.
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Sleep Basics and Duration
Start hereSleep need, duration, sleep debt, benefits, and the basics of how sleep works.
21 articles →Sleep Stages
Light sleep, deep sleep, REM sleep, and sleep cycle basics.
5 articles →Circadian Rhythm
Body clock, light timing, chronotypes, jet lag, shift work, and rhythm disorders.
10 articles →Dreams and REM
REM sleep, dreams, nightmares, lucid dreaming, and dream recall.
17 articles →Sleep and the Brain
Sleep pressure, memory, brain waves, alertness systems, and neurological sleep science.
8 articles →The systems behind sleep
Sleep is not a single state. Your brain and body move through stages, rhythms, pressure signals, temperature changes, and dream-heavy periods that each play a role in how rested you feel.
Use this section when you want to understand what is happening under the surface before choosing practical changes or treatment options.
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Sleep science
Sleep Stages
Learn how sleep laboratories identify N1, N2, N3, and REM sleep, how stages change through the night, and why a tra...
Sleep science
Circadian Rhythm
Learn how circadian timing, light, sleep pressure, chronotype, and melatonin shape sleep and when a persistent sche...
Sleep science
REM Sleep
REM sleep is a normal, recurring sleep stage measured from brain, eye, and muscle signals. Learn what tracker estim...
Sleep science
Why Do We Need Sleep?
Sleep supports alertness, learning, emotional function, and regulation across the body, although science has not re...