Catherine Zeta-Jones-being on top form a priority!

Catherine Zeta-Jones checked into a facility for a few days to treat her bipolar II disorder because she wanted to be on “top form” for when she returned to work.

The actress who’s married to actor Michael Douglas has two new movies coming up, including Playing the Field, currently in production in Louisiana with Gerard Butler and Jessica Biel, and Lay the Favorite.

“She went in for a few days because she’s about to start working, and to make sure she’s in top form,” a friend told People magazine, “which she is.”

Catherine’s rep confirmed news of the actress’ treatment in a statement Wednesday.

“After dealing with the stress of the past year, Catherine made the decision to check in to a mental health facility for a brief stay to treat her Bipolar II disorder,” the rep said.

“She’s feeling great and looking forward to starting work this week on her two upcoming films.”

Bipolar disorder, a mental illness marked by elevated or irritable moods alternating with periods of depression, afflicts about 6 million Americans. Those with Bipolar II tend to have more depression, with the mood swings spread over a longer time and the “up” periods less elevated. The episodes can be triggered by major stress or life changes.

“There’s no question it’s been a stressful year,” a source said.

“Catherine has had deal with Michael’s illness and that’s been hard. She went in for a few days because she’s about to start working, and wanted to make sure she’s in top form, which she is.”

Meanwhile, a source told the National Enquirer that Catherine “checked into rehab under the alias of Terrie Kirny. Michael was with her when she was dropped off.

“She was in the detox center with 10 to 15 other people.”