'Previous research has shown that humans signal their romantic interest in several different ways, including non-verbal behaviours and body language.'

London - Seeing a loved one in pain or ill is distressing. But now scientists think some people feel more than just empathy and actually experience the same symptoms.

These so-called “sympathy symptoms” are seen most famously in expectant fathers - one study found one in four dads-to-be experienced the same symptoms as their pregnant partners.

The men in the study reported food cravings, nausea and even complained of phantom pregnancy pains.

This is thought to be due to modern man’s desire to be closely involved with the pregnancy “experience”. It’s thought the constant monitoring of their partner’s progress in pregnancy has a powerful psychological effect on them, too.

The phenomenon is known as couvade, and it’s down to prolactin, a hormone strongly linked to pregnancy.

Prolactin is found in both sexes. It rises in women when they are pregnant and it goes up in expectant fathers, too, according to a study published in the journal Evolution and Human Behaviour. The higher men’s prolactin levels were, the more extreme the couvade - they put on more weight, suffered stronger aversions to certain foods and had more crippling nausea.

But pregnancy isn’t the only condition to cause sympathy symptoms. Studies show couples can share conditions, such as pain.

The psychological trauma of seeing a loved one suffer is powerful enough to create physical changes that lead to the same symptoms.

Studies using brain scans show witnessing a loved one or friend go through agony activates the same parts of the brain involved in the experience of first-hand pain.

A study by Heidelberg University in Germany showed that just hearing a partner moan in pain, without actually being able to see them, was enough to switch on those same brain responses.

So given that about 80 percent of us suffer from back pain at some point in our lives, for a few could it be just down to living with someone who is constantly complaining about their back?

German researchers found being exposed to regular back pain gripes significantly increased a person’s chances of having pain.

This is thought to be because their brain focuses so much on the problem that it mistakenly interprets their own normal everyday twinges and minor discomfort as chronic suffering.

The phenomenon may happen more with back pain because it’s so hard to pin down the cause - only about 15 percent of back problems have a known trigger.

Worse, feeling your loved one’s pain could have a damaging effect on your cardiovascular health.

Scientists at the University of Pittsburgh measured blood pressure and heart rate in the partners of people with osteoarthritis who were asked to carry heavy logs.

Seeing their loved ones in pain made their hearts beat faster and their blood pressure go up - both risk factors for heart disease.

But it’s not all bad news. Last year, a study in the Journal of Pain found rheumatoid arthritis patients in a strong marriage or relationship had less joint pain and better mobility than those who were single or in an unhappy marriage.

Experts believe the emotional stability of a strong marriage helps people to cope better with pain.

And if a patient’s illness relates to diet and lifestyle, such as type 2 diabetes, this may improve their partner’s health.

The condition, which leads to excess blood sugar, is usually caused by excess weight. When a couple are forced to improve their diet due to it, both will experience wide-ranging health benefits, not least through weight loss. - Daily Mail