(Cover) - EN Showbiz - Catherine Zeta-Jones chose to seek treatment for her bipolar disorder to make sure she was in top form before she embarked on work commitments.

The 41-year-old Hollywood star is believed to have spent five days at the Silver Hill psychiatric hospital in Connecticut last week. Her decision came after a tough year for the actress, in which she saw her husband Michael Douglas diagnosed with stage four throat cancer and his son Cameron sent to jail on drug charges. The stress of these events took their toll on Catherine and she chose to receive treatment before she began working on her new movies.

"Catherine has had to deal with Michael's illness, and that's been hard, a source close to Catherine told People. "She went in for a few days because she's about to start working, and to make sure she's in top form, which she is."

The star is due to begin shooting Playing the Field in Louisiana alongside Gerard Butler and has landed a role in Lay the Favorite, which also stars Bruce Willis.

During her time at the 770-a-day detox centre, Catherine is reported to have joined fellow patients for meals, exercised in the grounds and even played poker.

National Enquirer magazine has reported that an emotionally distraught Catherine checked into the hospital under the name Terrie Kirny and was accompanied by Michael when she arrived.

Catherine has previously revealed it can be difficult for her to remain positive and she is sometimes plagued by pessimistic thoughts.

"I'm lucky. But that's not to say I don't get down on myself, she explained. I try and stay positive, being negative isn't good for my personality. I don't just bring myself down, I bring everyone around me down. It's like a dark cloud, 'Uh oh, here we go', and I have to snap out of it." (C) Cover Media