Kristen Stewart was "asleep with her eyes open" when she won a Cesar award because she had no idea what was going on.

The 25-year-old actress recently became the first US star to win one of the prestigious awards at the French event, for her role in The Clouds of Sils Maria, but Stewart admits she spent most of the ceremony in a "meditative state".

Speaking to Conan O'Brien, Stewart said: "I went into a meditative state for that period of time. It was really long... like a four and half hour show or something, and they don't have commercials the way that we do, so we didn't get to take a break and chat and go to the bathroom and get a drink...

"I had a little earpiece for 30 minutes and then it stopped working and so I didn't even know when the category came up that was mine. I had fallen asleep with my eyes open, basically. And then Juliet screamed in my ear like 'You won!'

"I was genuinely just [really shocked]."

She added: "I was pretty nervous. This was kind of a big deal. I was joking with my publicist earlier that day because I was so nervous, I'm so you know completely fish out of water there anyway, and she was like, 'The worst that can happen is you win and you have to go up there and address the nation' so I was just really nervous!

"And I could not open my hands out! I was atrophied completely which was embarrassing, ridiculous."