Christopher Edginton was taking medication and trying to improve his diet when his cholesterol shot up anyway four years ago.

His doctor suggested a new approach. “He said you’ve got to get rid of some things you’re doing, some of the stresses in your life,” recalls Mr. Edginton, a professor at the University of Northern Iowa who regularly traveled internationally and had so many job titles that he had a four-sided folding business card.

Mr. Edginton heeded the doctor’s advice. Now 69 years old, Mr. Edginton is down to one teaching job and some scaled-down responsibilities in professional organizations. His level of so-called bad cholesterol, or low-density lipoprotein (LDL), has dropped to 62 milligrams per deciliter from 121 mg/dL in 2012. (The latest cholesterol-treatment guidelines, from 2013, no longer set specific targets; his doctor says 50 to 70 is reasonable for Mr. Edginton, who had two previous heart attacks.)

Of all the factors contributing to high cholesterol, many cardiologists say one often goes unmentioned in advice for patients: stress. Yet chronic stress from a tough job, a strained relationship or other anxiety-producing situations can play a role—along with poor diet, smoking and lack of exercise—in causing lipid concentrations to rise, they say. Cholesterol deposited by LDL can accumulate in the arteries, a condition known as atherosclerosis, which can reduce blood flow.

“Stress will make your cholesterol go up,” says Stephen Kopecky, a preventive cardiologist at the Mayo Clinic in Rochester, Minn., who is treating Mr. Edginton. “Without a doubt, that has been underrecognized.”

Understanding the effect of stress on cholesterol is becoming more important as people’s lives increasingly are crammed with obligations, and digital technology makes switching off harder than ever, cardiologists say. Nearly 28 percent of U.S. adults age 20 and older either have high total cholesterol or are on cholesterol-lowering drugs, according to the Centers for Disease Control and Prevention. The CDC defined high cholesterol as 240 mg/dL and above.

Click for more from The Wall Street Journal.