Ryan Reynolds

Ryan Reynolds is generally considered to be a hilarious and light-hearted Hollywood A-lister, but even he's had some terrifying movie experiences that would have wiped the smile off of his face.

While working on the flick 'Buried' – which sees a man wake up to find himself in a coffin – Ryan began to have panic attacks due to the claustrophobic environment.

He recounted: "One woman was playing all the roles when we were shooting. I had a microphone close to my chest, and she could hear my panic attack starting because she could hear my heart accelerating.

"There were times when I couldn't get out of the coffin with any ease, so I just had to stay in there with 50-60 pounds of wood on your chest pressing down so you start to have moments of panic."

The actor also revealed he suffered from insomnia due to the film.

He said: "I'd go home, and I'd pace until sun up, like a vampire, and then climb into a coffin to film. I was losing my mind; I hadn't slept in days, weeks."