Large numbers of people may be suffering in silence from the terrible condition of "sexsomnia" - somewhat like sleepwalking, but instead of wandering around the sufferer attempts to have sex with people.

According to results announced at a recent conference for sleep scientists, some 7.6 per cent of patients being treated for snooze-related disorders "reported that they had initiated or engaged in sexual activity with a bed partner while asleep".

"There have been no previous studies of how frequently sexsomnia occurs," said Sharon A Chung of the Sleep Research Laboratory in Toronto. "While our finding of eight percent of people reporting sexsomnia seems really a high number, it should be stressed that we only studied patients referred to a sleep clinic. So, we would expect the numbers to be much lower in the general population."

While happy to report sleep-shagging on a questionnaire, it seems that sexsomnia sufferers were much more reluctant to discuss their snoozy shenanigans face-to-face with a doc.

Chung noted that only four of 832 patients expressed a complaint about sexsomnia during a consultation with a sleep specialist.

"It seems that patients generally don't discuss this with their doctors," she said.

Readers may or may not be surprised to note that sleep-rogering is far more common in men (11 per cent) than women (four per cent). Sexsomniacs are also twice as likely as average to admit to illicit drug use, though there appears to be no link to smoking or caffeine.

A vast pdf collating all the SLEEP 2010 research (not just the sexsomnia) can be viewed here. ®