Courtesy The BBC

Sleepwalkers who have 'sex sleep'
People can act out their dreams
Imagine finding unexplained condoms around your house and then waking up one night to find your partner having sex with a stranger.

It might sound like an affair, but what if your "cheating" partner was fast asleep during the act?

The phenomenon, called sleep sex, was described to doctors at a meeting in Australia.

Sleep physician Peter Buchanan, from Sydney's Royal Alfred Hospital, described this real life case.

Mr Buchanan told the Australasian Sleep Association how a patient of his, who was a respectable middle-aged woman with a steady partner, would leave the house while sleepwalking and have sex with strangers.

The woman was totally unaware of her double life until her partner became suspicious and found her engaged in the act.

"He was aware of some sleepwalking and there was circumstantial evidence, including the unexplained presence of condoms around the house," Mr Buchanan told the conference.

Mr Buchanan ran a series of tests on the woman and diagnosed her problem - sleep sex.

This is a condition completely distinct from sleepwalking and is a form of sleep disorder called REM behavioural disorder.

Normally, when a person enters a phase of sleep called the REM (rapid eye movement) phase, in which we can often dream, our bodies are immobilised.

In the case of sleep sex, this doesn't happen and the person can act out their dreams.

UK sleep expert Neil Stanley from the Human Psychopharmacology Research Unit at Surrey University explained. CONTINUED ...