AP PSYCHOLOGY

Detailed explanation-1: -Stage 1 NREM sleep is the first sleep stage you enter when nodding off. This sleep stage is when heartbeat, eye movements, brain waves, and breathing activity begin to taper down. Motor movements also diminish, although you may experience muscle twitches called hypnic jerks.

Detailed explanation-2: -Stage 2: This period of light sleep features periods of muscle tone (muscles partially contracting) mixed with periods of muscle relaxation. Your eye movement stops, heart rate slows and body temperature decreases. Brain waves become slower.

Detailed explanation-3: -Stage 4: REM sleep This stage first happens about 90 minutes after you fall asleep. Your eyes move quickly from side to side during REM sleep. In REM sleep, your brain waves and eye movements increase. Your heart rate and breathing also speed up.

Detailed explanation-4: -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.