Widower Bill Farnsworth, who recently lost his wife of 33 years, knows how much grief can affect health. He already has lost weight and sleep.

"Beverly was Beverly. I've never met a woman like her, and I don't think I ever will again," the 67-year-old said. "Everything I ever needed or wanted, she took care of it. And for me to all of a sudden be lost, I was lost without her."

Now, even his daily tasks are a struggle.

"It's been tough, but each day gets easier. Each day gets easier," he said.

For some, it doesn't get less difficult, and the memory of a loved one's death may trigger something internally.

"We're reminded of the loved ones and the connection that we had and the fact that those no longer exist," said Dr. Jane Wright, of American College of Cardiology. "Our bodies are reacting to what our minds are sensing."

Researchers studied 102 sudden death cases of people between 37 and 79 years old. Most of the deaths — 70 percent — were caused by heart disease.

The study found men made up 80 percent of so-called anniversary deaths with 12 percent occurring on the same day as a parent's death.

"It's likely that men are more sensitive of everyday life, and on this anniversary day, in ways that cause their adrenaline to go up more than women," said Dr. Redford Williams of Duke University Medical Center.

But Williams put the odds of dying on a sad anniversary in perspective.

"The actual risk of a man dropping dead on the anniversary of the death of a loved one is probably not much higher than being struck by lightning on any given day," Williams said.

The study highlighted those who may be most vulnerable — people with high blood pressure, a history of heart disease, and diabetes.