The ancient Greeks said that Hypnos, the god of sleep, visited people during the dark of night to ease them into a state of rest. Hypnos hid from the sunlight during the day According to Greek myth, he was the son of Nyx, the goddess of night, and his brother was Thanatos, the god of death.
Some writers claimed that Hypnos lived in the underworld, but others said that he dwelled in a cave on the Greek island of Lemnos. Lethe, the river of forgetfulness, rippled through his dim, foggy cave. The Dreams, some of his many sons, lived with him. The most important ones were Morpheus, who caused sleepers to dream about people; Icelus (or Phobetor), who delivered dreams about animals or monsters; and Phantasus, who brought dreams about lifeless objects.
In the Iliad, Homer* tells a story about the goddess Hera* requesting help from Hypnos during the Trojan War*. She asked him to put Zeus* to sleep to prevent him from interfering on behalf of Troy. At first, Hypnos hesitated, fearful of Zeus's anger. However, Hera convinced him to help by promising him Pasithea, one of the Graces, as his bride.