Nightmare finds its etymological roots in the Old English word "maere," meaning "incubus," evolving through Middle English to describe a distressing dream experience. The Shudder Original film ‘Nightmare’ cleverly intertwines this concept with the haunting phenomenon of sleep paralysis, where individuals awaken unable to move or speak, often accompanied by terrifying hallucinations. In the film, Mona (played by Eili Harboe) suffers from relentless nightmares involving a demonic manifestation of her boyfriend, escalating her psychological torment.