South Australia is having a debate, and it’s about time. A discussion period on changes to the state’s time zone finishes this Friday.

South Australians, who are currently half an hour behind Australian Eastern Standard Time, have been given a choice: they can align their time with Western Australia, the Eastern states or make no changes.

Business groups have advocated since 2008 for aligning the state’s time zone with eastern states, while parents say their schoolkids will be spending an extra half hour in the dark in winter, especially in SA’s west.

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Flinders University psychology professor Leon Lack said when adolescents and young adults get less daylight their circadian rhythms get interrupted.

This can result in going to bed later, which would mean those affected would build up a sleep debt, become irritable and could doze off in dangerous situations like driving.

“For people who are dependent on that light early in the morning for their circadian rhythms, they would have a higher tendency to drift later, to become destabilised.”

“You get into this vicious cycle where on the weekend they catch up on their sleep cycle by sleeping in later but that then delays their body clock and makes it difficult to get to sleep early on Sunday night.”

Master Builders told the ABC that their costs would rise because construction workers in parts of the state would start work in the dark, meaning safety risks had to be ameliorated.

An online discussion forum has been organised to allow South Australians to comment on the proposal.

Garrin Ross said the eastern time proposal was “simply ridiculous”.

“Australia clearly has three distinct time zones, each separated by one hour and each time zone boundary is close to our longitudinal state borders,” he said.

“Currently the centreline of SA time zone … is not even in SA, it’s just to the east of Mildura in Victoria.”

One argument for moving to AEST is that television viewers were having their shows and sport spoiled because they begin in SA as they end in Sydney and Melbourne.

But David Peterkin said he wanted SA time to shift back towards WA.

“I can’t believe that people are so shallow as to want to move the time zone to match NSW and Vic simply to avoid spoilers with their TV viewing,” he said.

Only seven other places on Earth have a 30-minute time zone difference, the SA Government’s discussion page states.