IT came to symbolise modern life in a 24-hour society, but the often surreal experience of shopping in a giant supermarket in the early hours of the morning may be on the way out.

Tesco was the pioneer of the retail equivalent of the Windmill Theatre, never closing its doors. But the company has announced plans to change its service model at certain stores across the UK.

Staff members will no longer replenish stock during the night at some outlets, carnying out the tasks in the daytime instead.

The number of service counters will be reduced and they will no longer open throughout the day and night.

A total of 20 stores across the UK will cease to stay open 24 hours, with three in Scotland affected by the changes. These stores will move from 24-hour trading to opening between 6am and midnight from August 15.

The three in Scotland are Dundee South Road, Alloa and Glasgow Craigmarloch and Tesco insisted it would still have 50 stores north of the Border which would remain open through the night.

But Professor Leigh Sparks, Stirling University's Deputy Principal and Professor of Retail Studies, said there was no doubt the 24-hour model was under pressure.

He said: “These are the formats that have been struggling in face of the competition from convenience stores and also online shopping.

“The trade overnight in the superstores would have been people who would had gone in as they went to work.

"But now the sheer volume of convenience stores makes it much easier for these people to pick up anything locally. So they don’t need to go the 24-hour operations. That has taken volume out of the superstores.

“There were also some who would have wanted to go when it was quiet in order to do bulk shopping. Now a lot of these people have moved on to the internet.”

He said the changes planned were a reaction to the growth of convenience stores and the convenience of the internet.

He added: “When you think about it the model we built on, the hypermarket, was about consumers adapting their lifestyles to go to these stores.

"What has been happening in the last seven or eight years is retailers having to adapt their offer to suit the lifestyles of the consumers. Hence the small stores and internet, click and collect – now in conflict with the older model.”

He said there was evidence that the trend was more marked in Scotland than south of the Border.

“If anything in Scotland the trend would be accelerated as I think we have more convenience stores, per head of population than down south," he said.

"I have also seen figures which how we are more likely to buy on the internet, than down south."

Tesco said that there had been a change in the way their customers shop but the firm insisted that while the number of 24-hour stores may be reducing, internet retailing would remain a 24-hour operation.

A company spokesman said :“We’re making some changes to the way a small number of our stores operate, including three in Scotland, to help us run them more simply and deliver the best possible service to customers.

"Where there have been changes to a colleague’s role we will work with them to ensure they are fully supported.”

There are also a number of stores which do not currently trade 24 hours but have had a night shift team to restock the shelves.

In some of these stores, including Dumfries, Annan and Lockerbie, Tesco is moving to early morning replenishment.