Hypnos comes from the name of his Latin counterpart, Somnus. (in- "not" + somnus "sleep"), as well as a few less-common words such as "somnolent", meaning sleepy or tending to cause sleep and hypersomnia meaning excessive sleep, which can be caused by many conditions (known as secondary hypersomnia) or a rare sleep disorder causing excessive sleep with unknown cause, called Idiopathic Hypersomnia. 3D model of "Bronze head of Hypnos" via laser scan of a cast of British Museum's bronze. Hypnos In Greek mythology, Hypnos (; , "sleep") is the personification of sleep; the Roman equivalent is known as Somnus. In the
Greek mythology subterranean house of Hades and his predecessors, home of the dead. Influences from other cultures always afforded new themes. According to Classical-era mythology, after the overthrow of the Titans, the new pantheon of gods and goddesses was confirmed. Among the principal Greek gods were the Olympians, residing on Mount Olympus under the eye of Zeus. (The limitation of their number to twelve seems to have been a comparatively modern idea.) Besides the Olympians, the Greeks worshipped various gods of the countryside, the satyr-god Pan, Nymphs (spirits of rivers), Naiads (who dwelled in springs), Dryads (who were spirits of the trees),