Catherine Zeta-Jones enters a Mental Health Facility

Actress Catherine Zeta-Jones recently sought treatment for bipolar II disorder, a condition characterized by prolonged “low” periods, her rep confirmed Wednesday. Zeta-Jones, who checked into a mental health facility in Connecticut, has supported her husband Michael Douglas through his battle with throat cancer over the past year—and experts say such stress can trigger the condition.

Bipolar disorder, which affects 2 to 3 percent of the United States population, is defined by cycles of severe depression and manic episodes. People with bipolar II, meanwhile, swing from major depression to milder, briefer manic states, without experiencing full-blown manic episodes. Treatment typically involves medication and psychotherapy, which can dampen mood swings and related symptoms and can reduce episode severity and frequency.

“One of the things people often overlook because manias and hypomanias are splashy, is that most patients with bipolar disorder spend their lives depressed,” Martin Evers, an outpatient psychiatrist and associate director of behavioral health at Northern Westchester Hospital in New York, told Time. “The tragedy of the disorder is the depression. A lot of days of your life are lost.”