Sleep Science
Simple explanations of sleep stages, cycles, dreams, REM sleep, deep sleep, circadian timing, and what the brain does during the night.
These explainers keep the science approachable, so you can understand what happens during the night without getting lost in jargon.
Explore Sleep Science
The Stages of Sleep
Learn how N1, N2, N3, and REM sleep differ, how they cycle through the night, and why each stage contributes to healthy rest and daytime function.
What is the Circadian Rhythm?
Learn how the brain’s circadian clock uses light and daily timing cues to regulate sleepiness, alertness, hormones, temperature, and other body rhythms.
Why do People Dream?
Explore leading scientific ideas about why people dream, how dreams relate to REM sleep, memory and emotion, and why dream content can feel so vivid or strange.
REM Sleep
Learn what happens during REM sleep, why the brain is highly active, how dreaming and temporary muscle paralysis work, and how REM changes across the night.
What is Deep Sleep?
Learn what deep slow-wave sleep is, when it occurs, how it supports restoration and memory, and why trackers cannot measure it as precisely as a sleep study.
The Sleep Cycles
Understand how non-REM and REM sleep form repeating cycles, why cycle length varies, and how the balance of deep sleep and REM changes toward morning.
What Your Brain Does During Sleep
Learn how the brain stays active during sleep, organizing memories, regulating emotion, clearing waste, controlling body functions, and producing dreams.