Dear Fr. Fortea, can demons cause nightmares?
Yes, even though there is no way of knowing when a nightmare has a natural cause or a demonic one. We can only suspect that it has a demonic cause when there are other indications that point to this. There are cases where no psychiatrist has been able to find a reasonable explanation, either conscious or subconscious, for a normal person to suffer every night for a month or more with terrible nightmares that cause him or her to awake screaming and covered in sweat. These periods of very intense nightmares are sometimes connected to things such as having taken part in an occult rite or having begun a more intense spiritual life. The best advice one can give someone in this situation is to use holy water and ask God for protection and deliverance from any demonic influence during the night before he goes to sleep. If such actions cause the nightmares to stop, this would confirm that they were demonic in origin.
[The Spanish inscription in the illustration says, “The sleep of reason produces monsters!”]
Editor’s Note: To learn more about spiritual warfare and demonology, Catholic Spiritual Direction recommends Fr. Fortea’s excellent book Interview With An Exorcist – An Insider’s Look at the Devil, Demonic Possession, and the Path to Deliverance.
Art for this post on whether or not demons can cause nightmares: Caprichos No. 43, El Sueño de la Razón Produce Monstruos (Caprice No. 43, The Sleep of Reason Produces Monsters), Francisco José de Goya y Lucientes, 1799, PD-US author’s life plus 100 years or less; detail of Padre José Antonio Fortea 2017, photographed by Elgatoconbotaselgatoconbotas, 5 May 2017 own work, CCA-SA 4.0 International; both Wikimedia Commons. Cover of “Interview with an Exorcist” used with permission, all rights reserved.