A researcher from Australian and New Zealand College of Anaesthetists has raised concerns over the increasing number of patients complaining "sexual hallucinations" while under sedation.
Professor Barry Baker said it was common for patients to experience an erotic dream while under the influence of anaesthesia.
However, it could lead to complaints of sexual assault among those patients who were unable to differentiate the dream from reality.
"There have been some studies which have shown that up to 50 per cent of people who are sedated, or lightly anaesthetised, will have a sexual dream," The Australian quoted Baker as saying.
"If one person thinks they are anaesthetised it's a dream, if another person thinks they are wide awake and it's really happening then it's a hallucination," he added.
Baker said the increase could be linked to a rising use of sedation, as patients are deliberately asking for it before undergoing routine but otherwise uncomfortable or embarrassing medical procedures.
He said the increase in complaints was not - so far - linked to actual sexual assaults on patients.
"As far as I know there is no epidemic of sexual assault, far from it," Baker said.
"This is a sexual event that somebody believes happened to them in hospital and its not just about surgery, it can happen in the emergency ward or intensive care or anywhere a patient is sedated.
"It's a big issue for anaesthetists but they are not the most common people that are accused (and) if you go back over time the greatest number of people accused of some impropriety are dentists," he added.
Baker raised his concerns in a paper published in ANZCA's quarterly publication, the ANZCA Bulletin.