The actress, 40, revealed she bought the actor, 47, a luxury pillow at the end of filming because she was ‘concerned’ about how Cillian was sleeping.
Recalling the story, Emily, Cillian’s on-screen wife Kitty in the blockbuster movie, shared that he managed to smash his head on his bedside table after he missed his pillow as he lied down.
Speaking to The Sun, she said: ‘He’s going to kill me for telling this story. I was very concerned about Cillian’s sleep when we started shooting because I felt he had a monumental undertaking with this role.
‘He told me he woke up in the middle of the night and he was so thrilled to fluff himself back to sleep on the pillow, that he sort of threw his head down back on to it and smashed his head open on the bedside table.
‘He was luxuriating in it so much he smashed his head open. So he came to set and they had to glue his head shut, all because of the pillow.’
The Irish actor attended a screening of Christopher Nolan’s biopic at the BFI IMAX Waterloo on Wednesday, where he discussed the research that went into his role as the theoretical physicist credited with being the ‘father of the atomic bomb.’
Asked about the biggest lesson he took from his work on the movie, Cillian thoughtfully replied: ‘The main thing I learnt or relied upon was that he was a human being, that was the main thing I wanted to access – his humanity.’
The incredible physical transformation Cillian underwent for the role was revealed by his co-star Emily Blunt, who plays Oppenheimer’s wife Kitty.
Emily recalled how Cillian only ate an ‘almond a day’ and became ‘so emaciated’ as he immersed himself in the project.
Talking to Extra last year, Emily explained: ‘He had such a monumental undertaking’
Cillian himself told The New York Times: ‘I love acting with my body, and Oppenheimer had a very distinct physicality and silhouette, which I wanted to get right.
‘I had to lose quite a bit of weight, and we worked with the costume and tailoring; he was very slim, almost emaciated, existed on martinis and cigarettes.’
But Cillian made it clear that his extreme diet wasn’t safe and should not be tried by other people. ‘You become competitive with yourself a little bit, which is not healthy,’ he said, adding, ‘I don’t advise it.’
The breakneck pace of filming helped Murphy reach his weight loss goal.
‘It’s like you’re on this f***ing train that’s just bombing. It’s bang, bang, bang, bang. You sleep for a few hours, get up, bang it again,’ he told The Guardian.
‘I was running on crazy energy; I went over a threshold to where I was not worrying about food or anything. I was so in it, a state of hyper…something,’ he explained.
‘But it was good because the character was like that. He never ate.’
He is currently the bookies’ frontrunner to win the award and will compete against Bradley Cooper – Maestro; Colman Domingo – Rustin; Paul Giamatti – The Holdovers and Jeffrey Wright – American Fiction.