Hypnos is the god of sleep. His twin brother, Thanatos, is the god of peaceful death. The two of them sometimes work together to peacefully kill mortals in their sleep so they avoid suffering. He lives in a cave in the underworld where no light from either the moon or the sun shines. The cave is lined with sleep inducing flowers such as poppies and Lethe, the river of forgetfulness, flows through his cave. His parents are Nyx and Erebus and his wife is Pasithea. Their children are the Oneiroi, or the dreams.