Hypnos in Wikipedia

In Greek mythology, Hypnos (Ὕπνος, "sleep") was the personification of sleep; the Roman equivalent was known as Somnus. His twin was Thánatos (Θάνατος, "death"); their mother was the primordial goddess Nyx (Νύξ, "night"). His palace was a dark cave where the sun never shines. At the entrance were a number of poppies and other hypnogogic plants...

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