In his video interview, Tiller said he had been aware of the "nasty" allegations before being contacted by police.
"If it did happen, I would have been sleepwalking. I've never been to a specialist but did all those crazy stuff while asleep," he told Mr Bailey.
He said his partner was aware he was sleepwalking.
When asked what sort of things he did while sleepwalking, Tiller replied: "Getting changed for work, making sandwiches, jumping in the car with keys, switching on the TV, switching on the lights, and looking out the window."
Other times, he would wake up in peculiar positions.
Mr Bailey said it was called automatism - involuntary action or unthinking routine.
Tiller said he sometimes went to bed at 8pm or 9pm because he had to start work about 3am.
He admitted speaking to a complainant about the alleged abuse but said he could not recollect committing the alleged acts.
The complainant, he said, had approached him at work and on the street and asked about the alleged abuses.
Mr Bailey was the last Crown witness in the trial.
Defence lawyer Arthur Fairley will this morning indicate whether his client wishes to call or give evidence.
A closing address from both sides will follow before the jury of seven women and five men retire to consider their verdicts.
