Sleep stage

Sleep stage is a term used in sleep research to refer to the different phases of sleep that an individual goes through during a typical sleep cycle. These stages are characterized by different types of brain activity, and each stage has its own unique set of physiological and psychological characteristics.

Overview

Sleep stages are typically divided into two main types: REM sleep and NREM sleep. NREM sleep is further divided into three stages: N1, N2, and N3. Each stage is associated with specific brain waves and neuronal activity.

REM Sleep

REM sleep, also known as paradoxical sleep, is characterized by rapid eye movements, increased respiration rate and increased brain activity. REM sleep is also the stage during which most vivid dreaming occurs.

NREM Sleep

NREM sleep is divided into three stages: N1, N2, and N3.

N1

The N1 stage is the lightest stage of sleep, often referred to as somnolence or drowsy sleep. During this stage, the individual is somewhat aware of their surroundings and can be easily awakened.

N2

The N2 stage is characterized by sleep spindles and K-complexes on an EEG. During this stage, the individual becomes less aware of their surroundings and their body temperature begins to decrease.

N3

The N3 stage, also known as deep NREM sleep, is the deepest stage of sleep. During this stage, delta waves are present on an EEG, and the individual is least responsive to external stimuli.

Sleep Cycle

A typical sleep cycle lasts about 90 minutes and begins with NREM sleep. The cycle will progress from N1 to N2, then to N3, and finally to REM sleep before starting over again. This cycle is repeated several times throughout the night.

Importance of Sleep Stages

Each sleep stage plays a crucial role in maintaining good health and well-being. NREM sleep is important for restoring physical health, while REM sleep is important for cognitive functions such as learning and memory.

See Also

• Sleep
• Sleep disorders
• Circadian rhythm
• Dream

Sleep stage Resources
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