Usually symmetric, they occur each time the patient is aroused partially from sleep. V waves V waves are sharp waves that occur during sleep. They are largest and most evident at the vertex bilaterally and usually symmetrically. They show phase reversal at the vertex. V waves tend to occur especially during stage 2 sleep and may be multiple.
V waves are easy to recognize.
They are triangular in shape and generally symmetric. They occur in the awake patient and are said to be most evident when the subject stares at a blank, uniform surface. They can be multiple and usually are symmetric. Sleep spindles Spindles are groups of waves that occur during many sleep stages but especially in stage 2. They have frequencies in the upper levels of alpha or lower levels of beta.