Hypnos is the personification of sleep in Greek mythology. He is the son of Nyx and Erebus, and the twin of Thanatos ("death"). Both he and his brother live in the underworld. He gave Endymion the power of sleeping with open eyes so he could see his beloved, the moon goddess Selene.
Hypnos is portrayed as a naked young man with wings attached to his temples, or as a bearded man with wings attached to his shoulders.
Greek and Roman Mythology