David Hart, 59, claimed he had gone to a shower area to splash water on his eyes as he was feeling tired but sat down, dried his face and must have fallen asleep.

Mr Hart, who had worked for the company for 37 years and had a clean service record, was dismissed for gross misconduct but complained he was unfairly sacked from his job as a metal shop worker at Waukesha Bearings Ltd’s factory in Polmadie, Glasgow.

A Glasgow employment tribunal heard that Mr Hart, who suffers from high blood pressure and osteoarthritis, had been feeling unwell and was taking strong medication, including powerful painkillers, which his doctor confirmed could make him feel sleepy.

He slept through a six-minute fire alarm and was subsequently found lying on a bench in the shower area with his head resting on some towels being used as a pillow.

Mr Hart denied he had prepared a makeshift sleeping area or that his actions had been deliberate, adding he did not use a sink on the shop floor to splash his face because the hand basin was dirty.

He said he was embarrassed he had fallen asleep at work and expected to be disciplined, but never imagined he would be sacked.

Once he had splashed his face, Mr Hart, of Woodlands Crescent, Thornliebank, Glasgow, said: “I remember thinking I must sit down. I don’t remember anything after that.”

He denied he had deliberately gone to the shower room to sleep in the hope that he would not be discovered.

The tribunal, led by employment judge Shona MacLean, said their impression was that factory manager Michael Phelps had believed from the outset that Mr Hart had deliberately gone to the shower room to sleep while on duty and that the company did not carry out sufficient investigation before deciding to dismiss Mr Hart.

The tribunal noted that it was not unknown for employees to cat-nap during breaks and be woken by the nightshift supervisor. One employee had been found asleep in front of machinery and was awakened by the nightshift team leader and allowed to continue working. Another employee heard the fire alarm but failed to leave the building.

The tribunal found there was no contributory conduct on Mr Hart’s part and awarded him a total of £25,374 in compensation.

Mr Hart, who has since had an operation on his knee, originally wanted his job back but later decided there was no way he could return.

He said: “I am delighted I won. I feel I have been vindicated. ”