Actress Gillian Anderson terrified her kids with The X-Files by screening an episode of her cult sci-fi drama at home.

She sat Felix and Oscar down when she felt they were old enough to watch the show, and pressed play on what she deemed the “least scary” episode.

“It backfired so badly,” she told the hosts of U.S. TV show The Talk on Wednesday. “I literally chose the least scary of all of them, which also happens to be my favourite episode, which is called Bad Blood.

“They had nightmares for weeks! They’ve seen Harry Potter, they’ve seen (character) Voldemort, they’ve seen Orcs (in Lord of the Rings), they’ve seen everything.”

Anderson has reprised her role as Agent Dana Scully in The X-Files for the series reboot, which returns to U.S. TV on 24 January