PSYCHOLOGY OF EMOTIONS

Detailed explanation-1: -During normal sleep, a person goes through four to five sleep cycles that last about 90 minutes each and include both non-rapid eye movement sleep and REM sleep. Also called non-REM sleep and NREM sleep.

Detailed explanation-2: -The human body cycles through two phases of sleep, (1) rapid eye movement (REM) and (2) non-rapid eye movement (NREM) sleep, which is further divided into three stages, N1-N3. Each phase and stage of sleep includes variations in muscle tone, brain wave patterns, and eye movements.

Detailed explanation-3: -During REM, a person’s eyes move around quickly under closed eyelids. NREM (Non-Rapid Eye Movement) is the other phase of sleep. During NREM, the eyes remain still. The connection between REM and NREM is that these two phases make up a full sleep cycle.

Detailed explanation-4: -NREM sleep is divided into three sub-stages: stage N1, stage N2, and stage N3. Older classification had four stages of NREM sleep. In the current rules, NREM stage 3 and NREM stage 4 are combined as stage N3. Sleep stages occur in cycles lasting 90 to 120 minutes each.

Detailed explanation-5: -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.