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.