Matthew Perry put himself through on 'Friends'

Speaking on The Today Show, she said: "I didn't understand the level of anxiety and self-torture [that] was put on Matthew Perry, if he didn't get that laugh, and the devastation that he felt."

On the 'Friends' reunion special, Matthew admitted he felt like he was "going to die" while shooting every episode.

He said: "To me, I felt like I was going to die if they didn’t laugh.

It’s not healthy, for sure, but I would sometimes say a line and they wouldn’t laugh and I would sweat and just go into convulsions if I didn't get the laugh I was supposed to get. I'd freak out."

Matthew's admission shocked his co-stars including Lisa Kudrow, who played Phoebe Buffay.

Lisa replied: "You didn’t tell us that. I don’t remember you ever saying that."

And he admitted: "I felt that every single night."

Jennifer also opened up about her crush on David Schwimmer, admitting they still have a lot of love for one another.

She said: "I think there was something about unrequited love. I think David and I loved each other - we love each other still to this day - so I do think there was something that had to do with that. And you were investing in something that was very relatable: the one that you never could have or the one you wanted to be with but they couldn't quite get it together."