An absence seizure is a brief—5 to 15 seconds—but total loss of awareness that occurs suddenly without any warning and ends as suddenly as it begins. Absence seizures are most common in childhood and occur in people with generalized epilepsy of unknown cause.

The face muscles may twitch during the seizure. Although the person may appear to be awake, he or she cannot respond to anything or anyone. When the seizure stops, the person may resume normal activity without knowing that anything happened.

An absence seizure can sometimes be brought on by deep and rapid breathing (hyperventilation). During these few seconds of altered awareness, the person:

• Stares into space without moving.
• Stops speaking in mid-sentence, and their eyes may blink or flutter.
• Makes involuntary movements, such as lip-smacking, chewing, hand wringing, picking, or swallowing.

The person may have dozens or even hundreds of absence seizures each day.