Image from wikimedia
Hypnos, the daimon of sleep, resided in the dark land of Erebos. Nightly, he rose with his mother Nyx, whose name means night, and crossed the sky.
This image is typical, although he sometimes had not one but two wings sprouting from his brow. He might carry a stem of poppy, a dripping branch from Lethe, river of forgetfulness, or a horn of opium.
From this ancient god we get the words hypnotism and hypnotic, and from his Roman counterpart, called Somnus or Sopor, come the words somnolence and soporific.