Katherine Heigl shocked to hear Justin Chambers had checked in to a psychiatric ward

Katherine Heigl was visibly shocked when the paparazzi told her that Grey's Anatomy co-star Justin Chambers had checked himself in to the UCLA Medical Center psychiatric ward.

When asked Wednesday if she had heard that Chambers, a married father of five, volunteered himself to hospital, Heigl said: "Justin? When? I just spoke to him last week, he was fine."

A concerned Heigl, 29, then disappeared into LA eaterie, Il Piccolino, to make a number calls on her mobile phone, after hearing the news first hand from photographers.

Justin Chambers, 37, went to the UCLA Medical Center to seek treatment after suffering from exhaustion, and a sleeping disorder, a rep has said.

It is the same ward where pop star Britney Spears is currently being treated for her troubles.

Heigl and Chambers are both stars of hit medical drama, Grey's Anatomy.

The title of the show is a reference to the anatomy textbook Gray's Anatomy, and is a play on the name of one the prominent characters, Meredith Gray, played by Ellen Pompeo.