Historical note on sleep and eye movements.

Involuntary eye movements at the onset of sleep are mentioned in Virgil's Aeneid (19 BC). "Nystagmus" in relation to states of lowered consciousness was painstakingly catalogued by Sauvages (1768). Sporadic studies of eye behavior during sleep were recorded during the 19th century and were associated with disorders of brainstem physiology, culminating in von Economo's observations during the encephalitis lethargica epidemic of the 1920s.