Couples who share a passionate kiss this Valentine’s Day will enjoy sensations of relaxation and excitement because of a complex series of chemical processes, as well as their love for their partners.

The study showed that women need more than just a kiss to experience the same chemical high as men – with additional features such as a romantic atmosphere of dimmed lights and mood music also required.

Wendy Hill, professor of psychology at Lafayette College, Pennsylvania began the research to find out why the mundane physical activity of rubbing lips can elicit such a gratifying emotional response.

Her team tested the levels of two hormones, cortisol and oxytocin, in 15 couples before and after holding hands and kissing.

They found that kissing reduced the levels of cortisol, a stress hormone, in both sexes. But levels of oxytocin, a hormone linked to social bonding that they expected to be boosted by kissing, only rose among the men.

Implementing smoke-free policies can lead to a fewer hospitalizations resulting from heart attacks, according to a new study published by the Centers for Disease Control and Prevention.

Physically “acting out” dreams when asleep could be an early warning sign of dementia or Parkinson’s disease. Canadian researchers studied 93 people with “REM sleep behaviour disorder”, which can involve punching or kicking out while dreaming.

Canadian researchers studied 93 people with “REM sleep behaviour disorder”, which can involve punching or kicking out while dreaming.

The Neurology study found more than a quarter were diagnosed with a degenerative brain condition over the next five years.

UK experts said the research could help doctors predict the condition.

Normally, during “Rapid Eye Movement”, or “REM” sleep, our muscles relax and do not move, but people with certain sleep disorders are able to lash out, or cry out.

It is a known symptom of some kinds of brain disease, including Parkinson’s disease, and a rare form of dementia called Lewy body dementia.