Opening the trial, prosecutor Nicholas Campbell told Newcastle Crown Court that Nicholson, a former RAF military policeman, is expected to claim in his defence that the women were having "sexual hallucinations".

One woman, who cannot be named, told the court she was undergoing surgery on her shoulder in September 2008.

She said: "I woke up and felt a hand going inside the paper underwear and being placed on top of my genital area."

"I was very aware it happened. I didn't feel drowsy. I was very alert and felt very awake."

She said she felt the hand move away before returning to touch her again.

She added that the man and herself remained silent during the ordeal.

"I was just stunned because although there was no doubt in my mind it happened I guess it was just a sense of disbelief. I think that's just how I reacted. I didn't say a word, but I know it 100 per cent did happen," she told the court.

She contacted hospital bosses, police were called and Nicholson was arrested but denied the allegations.

The court heard how, after Nicholson's arrest, the hospital's director contacted a woman who had made allegations against a male nurse in June 2008 but had been too ashamed to report it to police.

She was persuaded to make a complaint to police.

Nicholson was again arrested but the woman failed to pick him out in a police ID parade.

Three other alleged victims also later came forward. One had been in hospital in March 2007 and the other two in June 2008.

Nicholson, of West Avenue, Harraton, denies six counts of sexual assault between March 2007 and September 2008.

In a police interview, Nicholson said that since his first arrest his son done research on the Internet about sexual hallucinations created by certain anaesthetics.

Mr Campbell said: "You will hear, however, that in each of these cases before you the complainants were conscious and awake, so dreaming can be excluded."