Slaapstadia

Slaapstadia, often referred to as sleep stages, represent distinct periods of the brain and body's activity during sleep. These stages are broadly categorized into two main types: Rapid Eye Movement (REM) sleep and Non-Rapid Eye Movement (NREM) sleep. NREM sleep is further divided into three stages.

NREM Stage 1 is the lightest stage of sleep, a transitional phase between wakefulness and sleep. Muscle activity slows, and brain waves begin to decelerate. This stage typically lasts only a few minutes.

NREM Stage 2 is characterized by a further slowing of brain waves, interspersed with brief bursts of rapid activity called sleep spindles. Heart rate and body temperature decrease. This stage constitutes a larger portion of overall sleep time than Stage 1.

NREM Stage 3, also known as deep sleep or slow-wave sleep, is the most restorative stage. Brain waves are very slow and large (delta waves). This is the period when physical repair and growth occur, and it is most crucial for feeling refreshed upon waking.

REM sleep is the stage where most vivid dreaming occurs. Brain activity resembles that of wakefulness, and voluntary muscle movement is temporarily paralyzed. During REM sleep, eyes move rapidly back and forth beneath closed eyelids. Heart rate and breathing become faster and more irregular.

These sleep stages cycle throughout the night, with each cycle lasting approximately 90 to 120 minutes. The proportion of time spent in each stage changes over the course of the sleep period, with deeper NREM sleep dominating the earlier cycles and REM sleep becoming longer in the later cycles. Understanding these stages is fundamental to sleep science and the study of sleep disorders.