Both Mary Shelley's novel and the monster's creation by Frankenstein within the novel were inspired by dreams. In the ‘Introduction’ to the 1831 edition of her masterpiece, Shelley wrote that her ‘hideous progeny’ (Shelley 2012, 169) came to her in a dream. As for Frankenstein, he describes his scientific endeavour as his life's dream (‘now that I had finished, the beauty of the dream vanished’) (Shelley 2012, 36). He also undergoes a series of abnormal sleep experiences throughout the novel, the most famous one being the dream of his fiancée Elizabeth turning into the rotting corpse of his mother, a disturbing scene which follows the monster's animation.

A well-known phenomenon called ‘the Nightmare’ bears striking similarities with both Victor Frankenstein's diegetic dreams and the oneiric circumstances of the novel's genesis. The OED (1989) defines this ‘Nightmare’ as ‘a spirit or monster supposed to beset people […] by night, settling upon them when they are asleep and producing a feeling of suffocation by its weight’. In Norse lore, the local Nightmare was a witch called Mara, from whose name both the English word ‘nightmare’ and the French word ‘cauchemar’ (in association with old French caucher, to tread on) derive. Linguists propose different etymologies for the word: móros (death), mer (to drive out) and mar (to pound, bruise, crush) (OED 1989). The latter, which is also the most probable root, is consistent with the victims’ feelings of oppression and terror. It was only later that the word ‘nightmare’ came to be used as a mere synonym for a bad dream. Originally though, bad dreams and nightmares were understood to be two very different phenomena. This distinction was corroborated by modern sleep science which identified evidence of physiological and cerebral activities specific to each case. In the field of sleep research, the nightmare experience is termed sleep paralysis.

Throughout this essay I will investigate the influence of this phenomenon on Mary Shelley's creative process in Frankenstein and the novel's ‘Introduction’, using modern medical descriptions of sleep paralysis, while also examining Mary Shelley's and her contemporaries’ understanding of the nightmare – from their own first-hand experience and from what they would have drawn from other intertextual or intermedial sources, notably folklore, mythology or painting.