Cillian Murphy didn't socialise while filming 'Oppenheimer' and he really needed a holiday once the shoot was over.

The actor plays plays physicist J. Robert Oppenheimer - known as the 'father' of the atomic bomb - in Christopher Nolan's dark new blockbuster and he's admitted he didn't go out much or socialise during the production because he was working so hard.

He told NME.com: "I didn’t go out much. I didn’t socialise much, mainly because of the amount of work I had to do … I became so immersed in the role."

The 47-year-old movie star added that he really needed a holiday once filming on 'Oppenheimer' wrapped because he'd spent six months preparing for the job and then worked 18-hour days while the cameras were rolling.

He went on to say: "You always have to take a holiday after a job. It’s not because… as some journalists like to think, you’re a method actor or whatever. It’s because you give so much time to the job and then suddenly you stop. You have all this displaced energy, you know, so you kind of don’t know what to do with yourself … But I’m a very easygoing sort of person. It doesn’t weigh me down."

However, Murphy admitted there was a sense of dread hanging over the cast during the shoot because they started work just days before Russia invaded Ukraine in 2022.

He added of the timing: " It [the war] was everywhere, and we were fully aware of that. The threat [of nuclear war] has escalated and receded over the years since 1945 … and now it’s back. It’s always there, this Sword Of Damocles that is hanging over us."