Agrypnia (from the Greek: to chase sleep) excitata (AE) is a syndrome characterized by loss of sleep and permanent motor and autonomic hyperactivation (excitata). Disruption of the sleep-wake rhythm consists in the disappearance of spindle-delta activities, and the persistence of stage 1 non-rapid eye movement (NREM) sleep. Rapid eye movement (REM) sleep persists but fails to stabilize, appearing in short recurrent episodes, isolated, or mixed with stage 1 NREM sleep. Diurnal and nocturnal motor, autonomic and hormonal overactivity is the second hallmark of AE. Of particular interest is the finding that norepinephrine secretion is extremely elevated at all hours of the day and night whereas the nocturnal melatonin peak is lacking. Oneiric stupor is probably an exclusive sign of AE and consists in the recurrence of stereotyped gestures mimicking simple daily life activities. Agrypnia excitata aptly defines 3 different clinical conditions, fatal familial insomnia (FFI), an autosomal dominant prion disease, Morvan syndrome (MS), an autoimmune encephalitis, and delirium tremens (DT), the alcohol withdrawal syndrome. Agrypnia excitata is due to an intralimbic disconnection releasing the hypothalamus and brainstem reticular formation from cortico-limbic inhibitory control. This pathogenetic mechanism is visceral thalamus degeneration in FI, whereas it may depend on autoantibodies blocking voltage-gated potassium (VGK) channels within the limbic system in MS, and in the sudden changes in gabaergic synapses down-regulated by chronic alcohol abuse within the limbic system in DT.