Sleep Basics & Science

The foundations of great sleep, explained clearly. Start here to understand stages, circadian rhythm, and how sleep drives brain and body performance. Start with our Circadian Rhythms guide to anchor your timing.

Featured

Starter

What Is Sleep?

A clear, practical breakdown of what sleep is from a biological and behavioral perspective.

Starter

Why Do We Sleep?

From memory consolidation to metabolic cleanup: the leading theories and what evidence says.

Fundamentals

Foundations

The Stages of Sleep Explained

NREM stages 1–3 and REM: what happens in each stage, and why cycling matters.

Foundations

REM vs Deep Sleep: Why Both Matter

Cognition vs restoration: how to think about balancing REM and slow-wave sleep.

Foundations

Circadian Rhythm Basics

Light, timing, and temperature: the core levers that set your body clock.

Research

How Sleep Affects the Brain and Body

Neuroplasticity, hormones, immune function, and long-term health outcomes.