The commemoration of the 70th anniversary of rapid eye movement sleep discovery offers a unique possibility to reassess the peculiar organic condition of agrypnia excitata. Agrypnia excitata is characterized by a severe loss of sleep leading to a complete derangement of physiological sleep-wake cycle and body homeostasis. Agrypnia excitata is a definite clinico-neurophysiological condition characterized by: (1) slow-wave sleep loss with disruption of sleepwake cycle
(2) a 24-hr motor and autonomic overactivity
and (3) peculiar episodes of oneiric stupor. Agrypnia excitata may happen within different pathophysiologies, such as delirium tremens, Morvan's syndrome and fatal familial insomnia, suggesting some general reflections on the composition and function of the cerebral neuronal network generating wake and sleep behaviour and regulating body homeostasis, with a focus on rapid eye movement sleep.