Typically, this type of seizure lasts between 10 and 30 seconds. The person, most often a child aged 5 to 15, abruptly stops whatever he's doing (talking, walking) and appears to "stare into space." Absence seizures rarely cause a true convulsion in which the person falls down or collapses. Despite briefly losing consciousness, the person recovers fully with no lingering confusion or other ill effects. These "spells" may occur infrequently or several times per hour. In children, absence seizures may interfere with learning and are often misinterpreted as daydreaming or inattention. About a quarter of people who have absence seizures will develop another type of generalized seizure called tonic-clonic seizures (formerly called ''grand mal'' seizures). The vast majority of children, however, will outgrow them.
In 50 to 60% of patients, epilepsy begins before the age of 16. In Western countries, the incidence in young children is declining, while incidence in elderly is increasing. Past studies show stable rates of overall incidence from 1935 to 1979. Differences in incidence rates in males and females are not statistically significant. There is no evidence of racial predilection in incidence, though the incidence is significantly higher in the lower socioeconomic classes.