AP PSYCHOLOGY

Detailed explanation-1: -In stages 3 and 4, deep sleep begins. Your eyes and muscles don’t move, and your brain waves slow down even further. Deep sleep is restorative. Your body replenishes its energy and repairs cells, tissues, and muscles.

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: -The most important sleep stage is Stage 3, Non-REM or, Delta (Slow Wave) Sleep, it takes up 25% of our total sleep cycle, and it’s known as the ‘deepest’ period of sleep. It’s in Stage 3 that sleep is at its most restorative, helping our bodies heal themselves and our minds rest.

Detailed explanation-4: -The first three stages are considered non-rapid eye movement sleep (NREM), while the fourth and final stage is rapid eye movement (REM). As the name suggests, REM sleep is distinguished by erratic eye movements behind closed eyelids, but there are other key differences between the REM and NREM stages.