Hypnos, Greek Mythology Link.
Sleep resembles Death.
It has been ordained that Hypnos and Thanatos should have all things in common. Hypnos, the younger, imitates the other in every thing. He can fashion shapes that seem to be true forms, and in his art he receives help from his sons. The abode of Hypnos. Hypnos, they say, has his abode within a hollow mountain in Cimmeria, which is to the north of the Black Sea.