---
title: "NREM Sleep — AP Psychology Definition & Exam Guide"
description: "NREM sleep is the three-stage, slow-wave phase where your deepest, most restorative rest happens. Learn how it contrasts with REM and shows up on the AP Psych exam."
canonical: "https://fiveable.me/ap-psych-revised/key-terms/nrem-sleep"
type: "key-term"
subject: "AP Psychology"
---

# NREM Sleep — AP Psychology Definition & Exam Guide

## Definition

Non-Rapid Eye Movement (NREM) sleep is a type of sleep that is divided into three stages and characterized by slow brain waves. It's the period of sleep where we get our deepest, most restorative rest.

## Related Study Guides

- [2.9 Sleep and Dreaming](/ap-psych-revised/unit-2/sleep-dreaming/study-guide/tIevfqX0AjCKuUQJ1DwU)

## Review

### Related Terms

- Stage 1 Sleep: This is the lightest stage of NREM sleep, often defined by the presence of slow eye movements. This stage serves as a transition between wakefulness and deeper stages of sleep.
- Stage 2 Sleep: The second stage of NREM where our heart rate slows and body temperature drops. Brain waves become slower with only occasional bursts of rapid waves called sleep spindles.
- Slow-Wave Sleep (SWS): Also known as deep or delta sleep, this is the third stage in the cycle where brain activity slows down significantly. It's during this time that our bodies repair muscles and tissues, stimulate growth and development, boost immune function, and build energy for the next day.