AP PSYCHOLOGY

Detailed explanation-1: -Stages 3 & 4: are known as deep NREM sleep. These are the most restorative stages of sleep. Stage 3 NREM sleep consists of delta waves or slow waves. Awakenings or arousals are rare and often it is difficult to wake up someone in Stage 3 sleep.

Detailed explanation-2: -Stage 3 sleep is also known as N3 or deep sleep, and it is harder to wake someone up if they are in this phase. Muscle tone, pulse, and breathing rate decrease in N3 sleep as the body relaxes even further. The brain activity during this period has an identifiable pattern of what are known as delta waves.

Detailed explanation-3: -In the deepest level of sleep, stage IV sleep, the predominant EEG activity consists of low frequency (1–4 Hz), high-amplitude fluctuations called delta waves, the characteristic slow waves for which this phase of sleep is named.

Detailed explanation-4: -Stage 3 and stage 4 of sleep are often referred to as deep sleep or slow-wave sleep because these stages are characterized by low frequency (up to 4 Hz), high amplitude delta waves (figuer below). During this time, an individual’s heart rate and respiration slow dramatically.

Detailed explanation-5: -Delta waves are associated with the deep sleep stages: stage 3 and REM. During stage 3, less than half of brain waves consist of delta waves, while more than half of brain activity consists of delta waves during REM sleep.