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. Hypnos's three sons or brothers represented things that occur in dreams (the Oneiroi). Morpheus, Phobetor and Phantasos appear in the dreams of kings. According to one story, Hypnos lived in a cave underneath a Greek island; through this cave flowed Lethe, the river of forgetfulness...

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