NREM

NREM or Non-Rapid Eye Movement sleep is a phase of human sleep characterized by minimal or absent rapid eye movement and reduced motor activity. It is divided into three stages: N1, N2, and N3, each representing a deeper level of sleep.

Stages of NREM Sleep

N1

The N1 stage is the transition phase from wakefulness to deeper sleep. During this stage, the brain produces high amplitude theta waves which are slow brain waves. This stage is sometimes referred to as somnolence or drowsy sleep.

N2

The N2 stage is the first actual stage of defined NREM sleep. Sleep spindles and K-complexes are predominant in this stage. These are sudden bursts of oscillatory brain activity generated in the reticular nucleus of the thalamus.

N3

The N3 stage is also known as deep NREM sleep. The highest arousal thresholds (i.e., difficulty to awaken) are observed in this stage. This stage is characterized by the presence of delta waves or slow wave sleep.

Functions of NREM Sleep

NREM sleep has several proposed functions including body and brain restoration, memory consolidation, and promoting growth and development.

See Also

• Sleep
• Rapid Eye Movement Sleep
• Sleep Cycle
• Sleep Disorders

References

NREM Resources
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