For most of his adult life, Coleridge was plagued by a ‘dreadful labyrinth of strangling, hell-pretending Dreams’ (CN iv 5375). There were also ‘<Scream-> Dreams’ (CN iv 5360), dreams which forced him to awake to a sense of ‘gouty suffocation’ (CN I 1833), and ‘Dreams of Terror’ (CN II 1998) which were accompanied by painful emotional and physical sensations (CN II 2838). He collectively referred to all such dreams as the ‘Afflictions of Sleep’ (CN iv 5360). However, the discomfort and anguish associated with nightmares did not prevent him from attempting to understand the many ways in which they could be distinguished from other species and genera of dreams.

In a letter to Poole of November 1796, Coleridge attempts to explain Charles Lloyd's illness. Lloyd had been staying as his pupil in Bristol for some weeks before the fits began:

Coleridge positions himself as an authority on the subject of ‘Somnambulism, or frightful Reverie, or Epilepsy … a kind of Night-mair’. He quickly distinguishes Lloyd's condition as not merely a ‘Night-mair’, but more specifically as a ‘kind of Nightmair’.