Sleep Science
The science of sleep explained — sleep stages, circadian rhythm, sleep drive, common myths, and how much sleep you really need.
New here? Read these in order
- 1The Stages of Sleep: What Happens When You Close Your EyesWhat happens across a night of sleep
- 2Circadian Rhythm Explained: Your Body Clock and How Light Sets ItYour internal clock, how light sets it, and why timing matters as much as duration
- 3Sleep Myths vs. Facts: What the Research Actually ShowsCommon beliefs checked against the research
See it work
All interactive guidesInteractive guides on this topic.
Your body clock: how light and melatonin move it
Watch light reach the eye and switch melatonin off, and darkness let it rise at dusk. Compare when melatonin rises and falls in an early bird, a typical sleeper and a night owl, then set the time of a light box and a dose of melatonin and step through a week to see the clock move earlier or later.
Open the guideTwo processes, one sleeper
Sleepiness is not one quantity but the distance between two: a pressure that builds while you are awake, and a clock that sets how much pressure it takes to put you under. Move the bedtime, try to nap, lose a night — and watch why six in the morning feels better than four.
Open the guideArticles
Circadian Rhythm Explained: Your Body Clock and How Light Sets It
How your circadian rhythm sets when you feel sleepy and alert, how light reaching the eye resets it each day, and why the timing of light matters.
Sleep Myths vs. Facts: What the Research Actually Shows
Separating common sleep misconceptions from evidence-based facts. What science really says about alcohol, naps, snoring, and more.
The Stages of Sleep: What Happens When You Close Your Eyes
Learn about the four stages of sleep, why each matters for your health, and what a normal night of sleep looks like.