What characterizes Sleep Stage 1?

Sleep Stage 1 is characterized by drowsy sleep that is easily disrupted, which accurately describes the transition between wakefulness and deeper sleep stages. During this initial stage, individuals may experience a light sleep where they can be readily awakened and might even have brief moments of awareness of their surroundings. This stage involves a reduction in muscle tone and activity, but the person remains in a relaxed, drowsy state, often associated with hypnic jerks or minor muscle twitches.

The nature of Sleep Stage 1 is transitional, with brain activity and muscle relaxation beginning to decrease from fully awake levels. This sets the stage for deeper sleep stages that follow. Consequently, while individuals may experience irregular breathing or other physiological changes later in the sleep cycle, these are not defining characteristics of Sleep Stage 1. Therefore, the emphasis on drowsiness and ready disruption aligns perfectly with the features characteristic of this initial sleep stage.