Scientists claim that lack of sex life can pose a serious health risk 

It is not uncommon for married couples of a certain age to lose some of their spark in the bedroom.

But over-50s who let their love life enter the doldrums should be aware it might be bad for their health.

A study of more than 5,700 found men who have less sex past 50 see their risk of serious illness rise by more than two-thirds.

Women are 64 per cent more likely to report being in ill health if they have sex less often, but there is no apparent significant rise in the risk of serious conditions.

Experts say those in middle age should remember the health benefits of a night of passion, which can burn 85 calories and releases feel-good endorphins thought to boost the immune system.

Men who become less interested in sex are 63 per cent more likely to be diagnosed with cancer and 41 per cent more likely to develop a long-standing illness, the study found.

Researchers who looked at people’s health over four years after they were questioned on their sex lives, say a decline in sex can also be a warning sign.

If individuals are too tired to make love, that fatigue can be a red flag for illness, while men suffering from impotence may have vascular problems which put them at risk of heart disease.

Dr Lee Smith, senior author of the study from Anglia Ruskin University, said: ‘It is important to remember that sex is a form of physical activity, albeit often performed at a moderate intensity, which burns around 3.6 calories a minute. All exercise comes with health benefits and sex is no different.’

The study, published in the journal Archives of Sexual Behaviour, looked at people in England aged 50 upwards – all participants in the English Longitudinal Study of Ageing.

Women are 64 per cent more likely to report being in ill health if they have sex less often, but there is no apparent significant rise in the risk of serious conditions

Among men whose libido had stayed the same or got better, just over 15 per cent developed a long-standing illness or disability such as diabetes or arthritis in the next four years.

But that rate was higher among men who said their sex drive had reduced, with one in five being diagnosed with an illness they said had affected them over a significant period of time, or was likely to.

The rate of cancer in these men was 6.7 per cent, compared with 4.3 per cent in those whose libido had not decreased.

Men who said they were having less sex than a year ago were 69 per cent more likely to have a long-standing illness.

Experts cannot say for sure whether a lack of sex leads to illness or if having less sex is a sign that someone is already ill before it has been diagnosed.