WASHINGTON (Reuters) - Songs that make our hearts soar can make them stronger too, US researchers reported this week.

They found that when people listened to their favourite music, their blood vessels dilated in much the same way as when laughing, or taking blood medications.

"We have a pretty impressive effect," said Dr. Michael Miller, director of preventive cardiology at the University of Maryland Medical Center in Baltimore.

"Blood vessel diameter improved," he said in a telephone interview. "The vessel opened up pretty significantly. You can see the vessels opening up with other activities such as exercise." A similar effect is seen with drugs such as statins and ACE inhibitors.

When blood vessels open more, blood flows more smoothly and is less likely to form the blood clots that cause heart attacks and strokes. Elastic vessels also resist the hardening activity of atherosclerosis.

"We are not saying to stop your statins or not to exercise but to add this to an overall program of heart health," said Miller, who presented his findings to a meeting of the American Heart Association in New Orleans.

Miller's team tested 10 healthy, non-smoking men and women, who were told to bring their favorite music.

They spent half an hour listening to the recordings and half an hour listening to music they said made them feel anxious while the researchers did ultrasound tests designed to show blood vessel function.

Compared to their normal baseline measurements, blood vessel diameter increased 26 percent on average when the volunteers heard their joyful music. Listening to music they disliked — in most cases in this group heavy metal — narrowed blood vessels by six percent, Miller said.

Miller said he came up with the idea after discovering the laughter caused blood to literally flow more smoothly.

"I asked myself what other things make us feel real good, besides calories from dark chocolate of course. Music came to mind. ... It makes me feel real good," he said.

Most of the volunteers chose country music but Miller said the style is not so important as what pleases each individual.