Adam Sandler has made a name for himself playing loud, brash, broadly comedic characters like Opera Man on Saturday Night Live and Bobby Boucher Jr. in The Waterboy. So it might surprise you to find out that he can seem somewhat shy in person.

At the press conference for Reign Over Me, Sandler shared the stage with costars Don Cheadle, Liv Tyler, and Jada Pinkett Smith, as well as director Mike Binder. But without a character to play, he was easily the least comfortable in front of the crowd of reporters.

Reign Over Me is a drama (with a serious infusion of comedy) written and directed by Binder (The Upside of Anger, The Mind of the Married Man). In it, Sandler plays Charlie Fineman, a man suffering from post-traumatic stress disorder after losing his family on one of the planes that hit the World Trade Center on September 11th. When his old college roommate, Alan Johnson (Cheadle), finds him roaming, zombie-like around Manhattan, the two rekindle their friendship.

Sandler wasn't initially sure he wanted the part. "The first time I read [the script], I thought it was a pretty incredible movie but I was afraid of it, so I just put it away," Sandler informed the crowd. "I told my guys, 'Yeah, tell that guy, "Thank you, but I can't do it,"' he continued. "I was kind of scared of it. And then one night like a month later it was next to my bed and I read it again, and it just was very moving to me. And I just couldn't stop thinking about it."

Luckily, when he approached Binder to see if he was still interested, no one else had been cast. "I can't articulate why I liked it so much, but it hurt my heart when I read it," Sandler said. "And it also made me laugh and I just wanted to accept the challenge."

In recent years, Sandler has been expanding his repertoire to include some more serious role, and a its good thing he did. "As soon as Adam's agent, Adam Venit, brought up the idea, I thought, 'That's a great idea, that's a great idea,' because I loved Punch-Drunk Love," said Binder. "I like how vulnerable Adam is even when he is in his craziest."

"We've gotten really close working on this movie, and I know why Adam is such a big star," he continued. "There's no mystery about it. When you get to know Adam, you don't think, 'Boy, this guy got lucky,' or 'This guy's been smart.' There's a humanity to this guy that people are smelling and seeing coming off the film."

But even with his experience on Punch-Drunk Love and Spanglish, Sandler felt that Reign Over Me was by far the biggest challenge. "I was pretty sure on Punch-Drunk Love I could do it," he said. "With this movie, every time Mike would tell me, 'Yeah you can do it, you can do it,' in my head I was like, 'I don't know. I don't know if I can do it.'"

As part of his research for the part, Sandler met people who had lost family and friends on 9/11, as well as those with post-traumatic stress disorder (PTSD), and even sat in on some one-on-one therapy sessions. "It wasn't easy for them," he explained, "but I would only come inside if they were okay with it. And if they needed me to leave, I would leave. But normally they just let me sit and hang out with them and listen. And they just wanted to get the word out about what they're going through."

For his part, Binder couldn't say enough about Sandler's work. "I was talking to my wife about it this morning. The job at hand, for what Adam had to do, was so layered in the complexity. At the same time he had to make it very simple," he said. "And his ability to just completely dive into the water and do what it took to get on the other side of this character so that he could just become this character."

"By the time he got on the set, it wasn't so much about, 'Okay today's scene I have to get in this place,'" Binder continued. "The footwork was there, that he had to just kind of be in each scene."

But playing such a heavy character did take its toll. "I had a headache almost everyday on the set, " said Sandler. "Normally with my movies, I go to my trailer, I have 10 guys hanging out with me, we're laughing, and then they're like, 'Adam come to set,' and I'm like, 'Ah, I gotta go do this,'" he quipped.

"This one I'm sitting there all alone, I'm just thinking...It was a lot of work, man," he went on. "Emotionally, I don't cry in real life. I'm just pretty light and I don't get too heavy. You know, I snap a lot, but I get over it pretty quick. This guy, this guy had a hold of his pain. And I tried to do so throughout the shoot as much as I could."

 After all that, it's no surprise Sandler is ready to go back to his usual comedic fare for a while. "I was hanging out with Cheadle the other day, and Don said, 'Any other serious stuff going?' I was like, 'You know after that one, I'm cool with just staying after that for a while.'"

Reign Over Me comes to theaters tomorrow, March 23rd.

Check of ReelzChannel.com's Reign Over Me page for clips of the movie and more!