Why are scientists so against daylight savings?

9 October 2023

Each October, a familiar debate resurfaces in the Australian media - the potential reintroduction of daylight saving time (DST) in Queensland, a topic that has been contentious since the 1992 referendum. In that year, the majority of Queenslanders voted to make standard time permanent. Supporters of daylight saving time suggest biannual clock adjustments or even a year-round daylight saving time. But why are scientists so against it? Let's delve into the research. 

Why have daylight savings?

Daylight saving was originally introduced under the hopeful pretence of significant energy savings but this aspect has since been debunked as showing no real benefits. Nowadays, much of the daylight saving time debate focuses on anticipated economic and social benefits stemming from extended evening daylight. While some data point to a modest decline in crime rates and traffic accidents because of later daylight, this beneficial effect is overridden by an increase of car accidents and heart attacks in the days following the transition to daylight saving time due to the lack of sleep and the associated lack of attention.

Other arguments for daylight saving time centre on its economic benefits that have been estimated to be around $4 billion per year for Queensland as daylight saving time allows people to do more after work. Yet, the scientific community remains largely united in opposition to daylight saving time.

Health impacts of daylight savings

Professional societies around the world with an interest in chronobiology, including the American Society of Sleep Medicine, the Society for Research on Biological Rhythms, and the European Society for Sleep Research, have consistently called to abolish daylight saving time. They argue for permanent standard time, underscoring the health burdens associated with it. 

Our internal body clock, or circadian clock, is integral to this discussion. This biological timing system, responsive to the natural changes in day and night, controls when we go to bed, but also many biological processes such as metabolism and immune function.

A bright sunrise aids waking up, while the evening’s low light promotes sleep. Daylight saving time disrupts this balance, leading to increased morning darkness and brighter evening light, delayed bedtimes and reduced sleep. This misalignment between internal clocks and social schedules is termed 'social jetlag,' and has significant health repercussions. Documented effects include inadequate sleep, decreased attention, increased metabolic and cardiovascular issues, mood disorders, and even a shortened lifespan.

Economically, sleep deprivation alone is estimated to cost approximately 2 per cent of a country’s GDP. For Queensland, this equates to an approximate loss of $9 billion per year, offsetting any anticipated economic benefits of daylight saving time and without even taking into account the additional costs associated with its health impacts and the burden on the health system. 

Towards an informed decision 

Although circadian clock research earned recognition through the 2017 Nobel Prize in Physiology or Medicine, it continues to receive inadequate interest and funding from governmental agencies. The existing studies, however, unequivocally illustrate the adverse effects of disrupting the circadian clock on our health and wellbeing.

Most political and economical debates about daylight saving time don’t include discussion about the significant health impact that it poses and the associated costs from those. In order to make an informed decision about adopting daylight saving time, a comprehensive approach needs to be taken. This will likely show that keeping standard time all year round is the better option. The debate should not be “Why don't Queensland, the Northern Territory and Western Australia have daylight savings?” but rather “Why southern states still do?”. 



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