Within Germanic folklore, there is said to be a demon called the "Mære/Mare" or "Mara" that was supposed to have wandered the night. It was thought to have been an immaterial being that could slip through keyholes and under doors. Upon reaching a sleeping person, it would crawl up and sit upon their chest. From there it would bring upon the sleeping victim a wealth of terrible dreams. This is the origin of the word "nightmare".

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