Robert Pattinson partying to deal with Twilight pressure?

Robert Pattinson partying to deal with Twilight pressure?

Some of the Twilight stars appear to be dealing with the pressure by hitting the party circuit -- to such a degree that it could be affecting their work, reports IN TOUCH.

"There's been a lot of tension surrounding the sequel," says a cast insider. "It's a stressful time for them right now."

Robert Pattinson, 22, who stars as brooding vampire Edward Cullen, is known for his rugged bad-boy image. But after a long night at Teddy's in Hollywood recently, he was especially disheveled for a business meeting about his latest film project, Parts Per Billion. "At least one person at the meeting noted that Rob looked a little worse for wear," reveals an insider close to the actor's camp.

, Kristen Stewart, 18, who plays mortal Bella Swan, has her own way of coping with the attention. "It's no secret that Kristen likes to unwind by smoking pot," says the cast insider.