Months before filming his first scene as a young Stephen Hawking for the romantic biographical drama "The Theory of Everything," actor Eddie Redmayne was already hard at work trying to embody the physical characteristics of the famed theoretical physicist. Hawking was diagnosed with ALS (amyotrophic lateral sclerosis) at the age of 21, a disease that over the decades has slowly robbed him of both movement and speech. 

Redmayne's preparation included working with a dancer to understand how ALS impacted Hawking's movements over time, as well as weekly visits to a motor neuron clinic in London. 

"[I] met a specialist called Dr. Katie Sidle, and I spent four months going to the clinic every week and meeting people with the disease and their families and talking to them," he told "They were incredibly generous with their time, going to some of their homes."

He added: "For me, I wanted all that physicality to be embedded in me, so when it actually came to playing opposite Felicity and Charlie, I didn't even have to think about it. It was much more about the emotional story, because that's the core in the film."

Redmayne explains that one of the great difficulties he experienced was the director's decision to shoot the movie out of sequence — forcing him to quickly speed up the physical disabilities experienced by Hawking. He was so nervous the day before shooting started that he couldn't sleep.

"On our first day filming the first scene was actually the scene that’s in the poster, so they’re young and he’s healthy and footloose and fancy-free, and then at lunchtime I was on two walking sticks, and then in the evening in the second wheelchair," he told RedEyeChicago. "So in one day it was putting all of those broad strokes of what the physicality was down, and I was so anxious the night before that it got till like 4 in the morning and I still wasn’t asleep. I was going, 'Do I take a sleeping pill? I’m being picked up at 5, then I’ll be completely groggy,' and I was having a complete meltdown. It was the only night of my life in which I’ve not slept at all."

Redmayne says that he had an osteopath on site every day to help realign his body after shooting. Nevertheless, even his director could see the physical impact the role was having on his star. 

"It did have a toll, no question; you could see it when we were filming," director James Marsh told the Evening Star. "There was a release any time we would shoot long takes with him. There was a release of ‘ugh,’ we’d say ‘cut,’ you’d just see it all kind of leak out of him … I feel terribly guilty."

Redmayne added, however, that his personal discomfort was nothing compared to those who suffer from ALS every day. “Whatever discomfort you were in, you got to step up out of the chair at the end of the day and a lot of people I met don’t have that.”

Check out a trailer for "The Theory of Everything" below.

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Michael d'Estries ( @michaeldestries ) covers science, technology, art, and the beautiful, unusual corners of our incredible world.

Eddie Redmayne and the physical challenge of playing Stephen Hawking in 'Theory of Everything'
Actor says he spent months working with experts to better understand the motor neuron disease the famed theoretical physicist suffers from.