AP PSYCHOLOGY

Detailed explanation-1: -Sleep occurs in five stages: wake, N1, N2, N3, and REM. Stages N1 to N3 are considered non-rapid eye movement (NREM) sleep, with each stage a progressively deeper sleep.

Detailed explanation-2: -Deep, slow brain waves known as delta waves begin to emerge during NREM stage 3 sleep-a stage that is also referred to as delta sleep. This is a period of deep sleep where any noises or activity in the environment may fail to wake the sleeping person. During this deep sleep stage, your body starts its physical repairs.

Detailed explanation-3: -There are traditionally 4 stages of sleep: awake, light, deep, and REM sleep. Each one plays an essential role in maintaining your mental and physical health. As you’re reading about sleep, you may also see the terms “NREM” or “NREM Stages 1-4.” These are simply other terms for the phases of sleep.

Detailed explanation-4: -During normal sleep, a person goes through four to five sleep cycles that last about 90 minutes each and include both non-REM sleep and REM sleep. Also called non-rapid eye movement sleep and NREM sleep.