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 the existence of this corpus of data is a strong indication that many elements of Greek mythology have strong factual and historical roots. Mythical narration plays an important role in nearly every genre of Greek literature. Nevertheless, the only general mythographical handbook to survive from Greek antiquity was the "Library" of Pseudo-Apollodorus. This work attempts to reconcile the contradictory tales of the poets and provides a grand summary of traditional Greek mythology and heroic legends. Apollodorus of Athens lived from to and wrote on many of these topics. His writings may have formed the basis for the collection; however the