“Once and Again” star Sela Ward has been secretly battling a thyroid condition that contributed to a recent collapse on the set.

The beautiful 45-year-old actress has lived through an extremely stressful year that included the cancellation of her TV show, the death of her mother and ongoing problems at her new Beverly Hills home.

And the strain, coupled with the thyroid condition, led to the collapse that sent her to a hospital for observation.

“Sela is battling an overactive thyroid and it’s taken a toll on her health,” said a source close to the actress.

Sela’s thyroid problem was diagnosed after she complained to her doctor of having trouble sleeping as well as feeling tired and agitated, said the source. And even though she was eating well, she was losing weight.

“The doctor said Sela’s problems were due to a thyroid imbalance, most likely caused by a virus,” the source revealed.

“Fortunately, her problem is highly treatable through medication and may go away entirely in time.

“But even though Sela took her medicine she continued to heap more and more work upon herself.

“In addition to the demands of her ABC show, Sela was also racing back and forth to Mississippi to comfort her mother, who was battling lung cancer.

“To complicate matters, Sela and her husband Howard were in the process of building a new home in Beverly Hills, which took much longer to complete than was anticipated.

“Then on February 12, she was hit hard by the death of her mother.

“And several weeks later Sela was hit again by the news her show and had been cancelled.”

Sela fainted on the set during the week of March 20 and was taken to a hospital overnight for observation. She didn’t return to work until the following week.

Now Sela is trying to remove as much stress from her life as possible.

Her spirits have been boosted by the news that “Once and Again” may be picked up again for the fall season, the source said.

“She was overjoyed. And she vows when she returns to the set she will be in good health.”