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 enters the sleep of mortals and gives them dreams of foolishness or inspiration, depending on the individual and their divine protectors or enemies. 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. The Romans had a similar deity named Somnus.