An expert witness testified Tuesday that 21 women who complained that a Toronto doctor had sexually assaulted them may have been dreaming.

Dr. Alan Aitkenhead, an award-winning specialist in anaesthesiology, was flown in from the United Kingdom by the defence to provide an alternate explanation for what is alleged to have happened in the operating room at North York General Hospital — and at one other location — to anaesthetized patients under the care of George Doodnaught.

Aitkenhead is an expert on the specific drugs — propofol and midazolam — Doodnaught used on the 21 patients who've made accusations against him.

Aitkenhead testified that the patients' allegations that Doodnaught fondled their breasts, kissed them and forced fellatio, could have been hallucinations caused by the drugs.

Doodnaught, 64. says he is not guilty of the 21 counts of sexual assault on women ranging in age from 25 to 75 over a four year period from 2006 and 2010.

During his testimony Aitkenhead made reference to a study done by an Irish doctor who investigated 21 complaints of similar sexual assaults under midazolam anaesthesia in medical settings.

The study found that witnesses were able to confirm most of the allegations and that the assaults could not possibly have happened, even though the patients had vivid memories and firmly believed they had.

"In terms of anaesthesia, having dreams of a sexual nature is not rare," he told the court. 

Aitkenhead's evidence contradicts the Crown's expert witness who testified that the chance of 21 complainants having all had sexual dreams "vanishingly rare."

Prosecutors say Doodnaught was able to sexually assault the women — even with a number of other doctors and medical staff in the room — because he was hidden by a drape set up to keep the surgery zone sterile.

The trial continues.