What is the term for a surface positive event that occurs in the occipital regions during drowsiness?

The term for a surface positive event occurring in the occipital regions during drowsiness is known as POSTS, or Positive occipital sharp transients of sleep. These transients are typically observed as brief bursts of positive waves and are considered a normal finding in the EEG during the drowsy state, particularly in the occipital areas of the brain.

POSTS are important because they can indicate that the individual is transitioning to deeper stages of sleep or are in a light sleep state. Their presence can provide clinicians with insights into the patient's neurological status and activities that are consistent with drowsiness, differentiating it from other phenomena that may be occurring in the EEG.

Mu rhythms, on the other hand, are associated with motor activity and are seen over the sensorimotor cortex, while K complexes are large, slow waves that occur mainly during sleep stages and do not specifically occur in the occipital regions nor are they associated with drowsiness. Alpha waves, typically observed when a person is awake but relaxed, do occur in the occipital areas, but they are generally present in a fully awake state rather than during drowsiness.