Jennifer Aniston on set

Jen Aniston Collapses

Bless Jennifer Aniston, she hasn't had an easy time so far this year.

Not a week goes by when there isn't some slice of gossip about her estranged husband Brad Pitt and his friend Angelina Jolie.

And the latest reports, that she collapsed on the set of her new movie, will worry her fans.

The Friends star fainted after complaining of nausea and headaches while filming The Break Up in Chicago, The Daily Mail reports.

She was officially diagnosed as having heatstroke, but sources on the set revealed to the paper that Jen's been badly affected by all the rumours about Brad and Angelina - and the constant whispers that they are, in fact, lovers.

Only yesterday it was revealed the pair were in Ethiopia, where Brad was helping Angelina adopt an Aids orphan.

Although they have not confirmed they are a couple, photos of them hanging out together - along with Angelina's son, Maddox - are constantly appearing in papers and magazines, and Brad has recently bought a pad in the next village to Angelina in Buckinghamshire.

A source on the set of Jen's new film told The Daily Mail: "She's been walking around with a sad look on her face and has not been her usual self.

"She has talked about how she is not sleeping well, although she has been trying to be as brave as possible.

"She can't have escaped all the stories about Brad and Angelina and it looks like the situation has taken a toll on her.

"While her collapse was blamed on heatstroke, everyone thinks it is more down to stress than anything else."

Recently there was excitement after Jen and her co-star Vince Vaughn were spotted hugging and looking all cosy - but they have both since denied they are anything more than good friends.