London: New research reveals a surprising new therapeutic benefit of relaxing in a sauna: getting hot and sweaty can not only release "happiness molecules" but also help your heart.

This week British science magazine New Scientist reported on the research, which found that people with chronic heart failure who took fives saunas a week for three weeks enjoyed improved heart function and a boost in their exercise endurance.

In the study, researcher Takashi Ohori and colleagues at the University of Toyama in Japan asked 41 volunteers with heart failure to take a 15-minute sauna fives time a week. After the sauna treatment, participants were asked to wrap themselves in a blanket for 30 minutes to keep their body temperatures about 1 °C higher than normal.

"Sauna treatment increased the heart's ability to pump blood, and boosted the distance participants could walk in 6 minutes from 337 metres to 379 metres," wrote New Scientist.

The researchers also found improved function in the membrane lining the inside of the heart, which plays a role in controlling the diameter of blood vessels. The findings were published in The American Journal of Cardiology.

Thanks to the increase in body temperature, separate research has found that a sauna treatment can trigger neurons in your body to release serotonin, resulting in a feel-good sensation.