Hypnos is the Greek personification of sleep. He is a divine power rather than simply a poetic name for tiredness. Ancient genealogies usually make him a son of Night and a brother of Thanatos, Death, though details of his dwelling and family vary.
Sleep in the Iliad
Hypnos plays a major role when Hera asks him to put Zeus to sleep so that she can aid the Greeks at Troy. Hypnos remembers an earlier time when he helped Hera and barely escaped Zeus’s anger by taking refuge with Night. He agrees only after Hera promises him Pasithea as a wife.
Once Zeus sleeps, Poseidon can help the Greek forces. The scene shows that even the highest god can be overcome temporarily by sleep, while also showing Hypnos’s fear of Zeus. It is a divine bargain inside the poem, not a general claim that Hypnos always controls Zeus.
Sleep, death, and dreams
Greek art sometimes shows Hypnos and Thanatos carrying the dead warrior Sarpedon. Their brotherhood links sleep with death while keeping them distinct. Later writers name dream figures such as Morpheus, but Morpheus should not be substituted for Hypnos. Sleep and a particular shaper of dreams have separate identities.
Hypnos’s family connection to Night can be compared with Eris, whom Hesiod also calls a daughter of Night. The underworld associations of Hecate arise from another set of texts and rites.