"Demons" is the twenty-third episode of the fourth season of the American science fiction television series The X-Files.

The show centers on FBI special agents Fox Mulder (David Duchovny) and Dana Scully (Gillian Anderson) who work on cases linked to the paranormal, called X-Files.

This marked the second instance where a member of the production crew wrote an episode, after the third season entry "Wetwired", written by Mat Beck.

The episode was influenced by An Anthropologist on Mars, a series of essays by Oliver Sacks, in particular The Landscape of Dreams featuring a man who could recall every detail of his childhood.

Fox Mulder's (David Duchovny) mind flashes back to being in the attic with his sister Samantha while their parents are arguing downstairs.

When they arrive there, Mulder has striking pains in his head and flashes back again to when he was a child, seeing a younger version of The Smoking Man (Chris Owens) in his home.

The agents visit Dr. Goldstein in Warwick, Rhode Island, who was treating Amy with an aggressive method to help her recover her abduction memories.

Mulder declines Scully's request that he go to the hospital and goes to visit his mother, demanding she explain what really happened when they had to make a choice between him and Samantha.

[2] After receiving approval from series creator Chris Carter, Goodwin spent approximately six weeks writing the final episode.

[4] The episode is based around the idea that Geschwind syndrome (a group of behavioral phenomena, of which one is the ability to recall every memory of one's younger life) can be self-induced by using a unique combination of technology and drugs—something that is not supported by modern medicine.

When writing the episode, Goodwin was aware of the idea's implausibility and admitted that he took significant creative liberties with the disorder.

In fact, the technology used in the episode to induce Mulder's flashbacks was based on various New Age equipment, including a "brain stimulator".

The show's art department rented and refurbished the house, took photographs of the building, then returned it to its original state for the actual filming.

[2] The show's camera operators and editors made use of several distortion techniques to give the flashback sequences a hazy, uneasy, and "dystemporal" feel.

To add to the sense of disorientation and confusion, the scenes' dialogue was mixed in with ambient background noise by producer Paul Rabwin.

"[10] The author argued that the attention given to Mulder's potential "aneurysm" are oddly juxtaposed next to Scully's real, life-threatening brain cancer.