Sleepwalker's sex in the city
By day, she was a respectable middle-aged woman who lived with a steady partner. By night, she would creep out of their house to seek random sex with strangers.
But the woman in question was entirely unaware of her double life, which was conducted while she was asleep, said the Sydney doctor who treated her.
"Incredulity is the first staging post for anyone involved in this," - including medicos, said Peter Buchanan, a sleep physician at Royal Prince Alfred Hospital.
"One has to maintain a healthy degree of scepticism. As doctors we are largely trustful of our patients telling us the truth about themselves."
In this case, though, it was clear the woman's story was not an ingenious cover for clandestine sexual flamboyance. The patient was baffled; her partner distraught. "He was aware of some sleepwalking and there was circumstantial evidence, including the unexplained presence of condoms around the house," Dr Buchanan said.
"On one occasion he awoke to find her absent from the bedroom and searched until he found her - engaged in such activity."
Her condition, known as sleep sex, is a recently identified sleep disorder, Dr Buchanan will tell the Annual Scientific Meeting of the Australasian Sleep Association in Sydney this weekend.
Sleep sex is increasingly being recognised as a real and personally devastating condition, said Dr Buchanan, who expects it will be included in the next revision of the International Classification of Sleep Disorders, giving it the final stamp of legitimacy. It is fraught with personal danger through risky sex practices, and legal danger - if the sufferer commits sexual assault while sleepwalking.
Dr Buchanan said it was hard to confirm the diagnosis, because staying overnight in a sleep laboratory would generally inhibit the behaviour. But in the woman's case, brain tests while she was sleeping showed she was unusually likely to rouse from deep sleep without passing first through lighter sleep patterns - a phenomenon linked to all types of parasomnia.
Almost half of sleep sex cases were associated with psychological problems, and the woman was treated successfully with psychotherapy. But the fact that the condition manifested as aberrant sexual behaviour did not indicate sexual abuse or any other sexual problem, said Dr Buchanan, and it should be viewed as a sleep disorder, not a sexual disorder.
"There's a huge embarrassment about seeking medical help," he said.