There are multiple health risks associated with the change to daylight saving time.
There are multiple health risks associated with the change to daylight saving time.

Daylight saving linked to health risk

In just a few weeks time many parts of the country make the switch daylight saving time (DST) but there is growing proof that turning the clocks forward could actually put people's health and safety at risk.

There have been increased calls around the world in recent years to cancel DST due to scientists finding links between the time change and a spike in health problems, road accidents, mood changes and even medical mistakes.

Studies that have been conducted into daylight saving have found these heighten risks mainly stem from the body's circadian rhythms being disrupted.

Circadian rhythms are the 24-hour cycles that relate to the body's internal clock, which determines when certain signals and essential functions are carried out.

Daylight is one of the most powerful cues that set off these biological processes, with a study conducted by the American Academy of Sleep Medicine (AASM) finding the change to DST can cause a "phase delay" in the circadian rhythms.

"The acute alterations in timing due to transitions to and from DST contribute to misalignment between the circadian biological clock and the light/dark cycle, resulting in not only acute personal disruptions, but significant public health and safety risks," the study found.

The switch to daylight saving time in spring, where clocks are turned forward an hour, appears to have more negative impacts than the change back to standard time.

Research has shown there is an increase in heart attacks, strokes and other heart-related issues shortly after changing to DST.

"An increase in missed medical appointments and increased emergency room visits and

return visits to the hospital are also seen only during the spring transition from standard time to DST," the AASM study noted.

"The one-hour time shift in the spring results in less exposure to light in the morning and greater exposure to evening light. In the presence of continuing social or occupational demands in early morning hours, this delay results in sleep loss and resultant sleep debt."

The "cellular derangements" resulting from the switch can also lead to other health issues, including a higher heart rate, higher blood pressure and reduced ability to sleep.

The study warned these impacts can lead to severe mood changes and, in extreme cases, have been associated with suicide.

"Although most acute health-related effects are noted only when transitioning from standard time to DST, transitions both into and out of DST have been associated with sleep disruption, mood disturbances and suicide," the study reads.

Studies have found having an one hour less of sleeping time when switching to DST can have a range of adverse impacts. Picture: iStock
Studies have found having an one hour less of sleeping time when switching to DST can have a range of adverse impacts. Picture: iStock


It isn't just the health impacts that people who follow daylight saving need to be concerned about, with the change also linked to a spike in road accidents.

Traffic accidents have been shown to increase in the first few days after DST, with crashes increasing by up to 6 per cent in the US, according to the AASM research.

Another bizarre change that researchers have linked to DST is a sudden volatility in the stock market.

"While reasons for this are not entirely clear, proposed mechanisms include the impact of sleepdeprivation on frontal lobe functioning, which may result in impaired judgment and decision-making capacity," the study noted.

Another study, conducted by the Sleep Research Society, found the reduced sleep associated with moving clocks forward an hour can lead to a spike in medical errors.

Researchers examined the rate of "adverse medical events" cause be human error in the week before and after daylight saving over an eight-year period.

Preliminary results found there was an 18 per cent medical mistakes relating to human error after the change to DST.

This was significantly higher than the 5 per cent increase in errors recorded following the return to standard time.


The debate around whether to cancel daylight saving has been going on for years but it ramped up last year when the European parliament voted to scrap changing the clocks from 2021.

From next year, countries that are part of the EU will be able to choose whether they want to stay on permanent summer" or "permanent winter" time.

Under the proposal, those that chose permanent summer would adjust their clocks for the last time on the last Sunday of March 2021, and those that choose winter will do so on the last Sunday of March 2021.

The debate over whether the change in time twice a year is necessary has been ongoing in Australia, with only NSW, Victoria, the ACT, South Australia and Tasmania still observing DST.

Yesterday, An Australian professor spoke out about some of the health risks associated with changing the clocks, warning the health risks could be amplified by the COVID-19 pandemic.

Professor of diabetes at Monash University, Paul Zimmet, told 3AW health authorities needed to consider the negative impacts of the upcoming change to daylight.

"In terms of the scientific evidence, which we will want to stick with at the moment, there are more heart attacks just after daylight saving, more road accidents, and then you've got workplace accidents, car accidents and their implications," he said.

"There is also cognitive dysfunction in relation to the daylight saving and the change in timing to our normal body rhythms."

A poll conducted by showed many Aussies want daylight saving to stick around, with 65 per cent of the 38,500 voters choosing to keep the time change.

Victorian Premier Daniel Andrews shut down the possibility of cancelling daylight saving when asked about Prof Zimmet's comments during Wednesday's press conference.

"I don't want to be disrespectful to the professor, who may be a very learned individual. No. Daylight saving will be proceeding," Mr Andrews said.

"That's why the curfew changes, that extra hour is really important, well ahead of daylight saving."

Mr Andrews said the extra hour of daylight would hopefully help make the summer "like no other".

"This will be a summer like no other and daylight saving, I can confirm, will be a feature of it."

Daylight saving will kick off at 2am on October 4, with residents in NSW, Victoria, the ACT, South Australia and Tasmania turning their clocks forward by an hour.

Originally published as Big reason to scrap daylight saving time

Researchers have discovered the change to daylight saving time can have multiple impacts on people’s health.
Researchers have discovered the change to daylight saving time can have multiple impacts on people’s health.