Gillian Anderson suffered from headaches because of the wig she had to wear for 'The X-Files'.
The 47-year-old actress has returned to her role as Dana Scully in the TV series but opted for a wig to recreate her infamous red hair as she needed her blonde locks to film 'The Fall' so soon afterwards.
She told the Metro newspaper: "A wig has to be very tight, so it's a bit like wearing a vice for 17 hours. You get used to it, but you start the first couple of weeks with headaches.
"I felt a bit fake in the beginning, but eventually it becomes part of how Scully now felt."
Meanwhile, the 47-year-old actress previously revealed she was told her hair would fall out if she dyed it anymore.
She said: "I was told my hair would fall out if I dyed it and then went straight back to blonde for 'The Fall.'"
And Gillian also admitted shooting the new series had been "physically challenging".
She added: "I was ambivalent about the idea at first. In its old incarnation, we used to do 24 shows a year. But I can't do that any more, so it only became a reality once the networks started to be a bit more lenient about the number of episodes they were willing to air.
"What was weird once we started was that it was both strange and familiar. We're both a lot older now. I used to be able to run forever, but now I'm, like: my legs aren't working. The physical side was ... challenging."