1911 Encyclopædia Britannica/Somnus

SOMNUS, the Latin name for the personification of sleep, in Greek Hypnos (Ὕπνος). He is the son of Night and the twin brother of Death, with whom he dwells in the darkness of the underworld. At first the difference between the two is strongly marked. While Death is cruel and merciless, and never lets go his prey once seized, Sleep is gentle and kindly, the bestower of rest and pleasant dreams, the soother of care and sorrow. Even Zeus is unable to resist his influence, and on two occasions was put to sleep by him at the instance of Hera. In time, however, the conception of Death was greatly modified, until at last he was depicted as a beautiful boy, with or without wings. In like manner, Sleep came to be used as a euphemism for Death. In art the representations of Sleep are numerous and varied. On the chest of Cypselus, Night was depicted holding in her hands two sleeping children—one white (Sleep), the other black (Death). His most common form is that of a vigorous young man, with wings on his forehead; his attributes a stalk of poppy, and a horn from which he drops slumber upon those whom he puts to rest. In Ovid (Metam. xi. 592) the home of Sleep is placed in a dark grotto in the land of the Cimmerians, where he dwells surrounded by a band of Dreams.

See Homer, Iliad xiv. 231—xvi. 672; Hesiod, Theog. 212, 758; Pausanias, v. 18, 1.