The concept of 'awakening epilepsy' (introduced by Janz, 1953) occupies a crucial position for the comprehension of primary generalized epilepsy. The associated electroencephalographic manifestations are discussed and the role of abnormal (paroxysmal) arousal responses ('dyshormia') is stressed. The origin of these bilateral-synchronous discharges appears to be located below the frontal midline scalp region in mesial portions of the supplementary motor region. 'Awakening epilepsy' is also interesting from the viewpoint of sleep research. There is also an important age factor; these seizures (mostly grand mal and classical petit mal absences) are most common in older children, adolescents and young adults. The general management of these patients has to take into account the patient's special vulnerability after a night of poor sleep.