What stage of sleep occurs during the transition from wake to sleep?

Stage 1 sleep is characterized as the initial phase of the sleep cycle, marking the transition from wakefulness to sleep. During this stage, individuals typically experience light sleep, where they can be easily awakened. Physiologically, it involves a decrease in heart rate, muscle relaxation, and diminished brain activity compared to wakefulness. It typically lasts only a few minutes and can include hypnic jerks or brief muscle contractions.

In contrast, Stage 2 is a deeper sleep where sleep spindles and K-complexes occur, indicating a transition to more stable sleep. Stages 3 and 4 represent slow-wave sleep, which is much deeper, while Stage 5 is associated with REM (Rapid Eye Movement) sleep, where dreaming often occurs. Thus, Stage 1 is specifically recognized as the point during the sleep cycle when a person moves away from active waking and begins the sleep process.