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Scientists have issued renewed calls for Daylight Saving Time (DST) to be ditched amid fears it fuels a rise in cancer and potentially deadly traffic accidents.
In the early hours of tomorrow morning the clocks will jump back an hour, giving everyone a bit longer in bed.
But rather than celebrate having a lie–in, experts have warned it could have a slew of unexpected consequences and say it should be 'absolutely' be abolished.
The practice was first introduced in 1916 in a bid to improve workforce productivity by making the most of daylight hours in the summer months.
It means the clocks go forward by one hour at 1am on the last Sunday in March, and back one hour at 2am on the last Sunday in October.
The argument is that as the days get longer, shifting our schedules forward gives people more sunlight hours during their working day.
However, mounting evidence highlights the negative effects of the biannual shift.
Losing an hour of sleep when the clocks move forward can result in the whole population feeling more tired than usual.
In the early hours of tomorrow morning the clocks will jump back an hour, giving everyone a bit longer in bed (stock image)
Some studies have suggested that the risk of fatal traffic accidents increases by around six per cent following the spring daylight savings time transition.
There is also evidence of an increased risk of cardiovascular events, increased risk of suicidal behaviours and increased mortality in the days after switching our clocks.
Meanwhile, our bodies rely on bright morning sun to keep our body clocks aligned with the normal 24–hour solar cycle.
There is a growing – although somewhat contested – body of evidence that a mismatch between the sun and our bodies can have severe long–term health impacts.
Studies have shown that those living in the West of a time zone – where the mismatch between the sun time and our body clocks is greatest – have higher risks of leukaemia, stomach cancer, lung cancer and breast cancer.
Since this mismatch is very similar to those experienced when the clocks go forward, some scientists say daylight savings might be having a similar impact.
Dr Jeffrey Kelu is a researcher at King's College London who specialises in circadian rhythms, cycles of around 24 hours that help govern bodily functions like the sleep–wake cycle.
He said evidence shows keeping to one time zone throughout the year would be better for our health.
Top scientists have called for an end to Daylight Saving Time (DST), amid fears it fuels a rise in cancer, traffic accidents and suicide
Why do we change the clocks at all?
You might think there’s a scientific reason, linked to the positioning of the sun.
However, the clock change is actually a practice that began during World War I.
In the spring of 1916, the German army turned their clocks forward to conserve energy, by making better use of daylight.
Shortly afterwards, many other countries – including the UK – followed suit, in an effort to aid the war effort by saving energy resources.
However, the benefits of the clock change have been an ongoing debate in the 109 years since it was introduced.
Campaigners believe we should return to permanent British Summer Time to increase the time available in the evenings, while opponents claim this would create social disadvantages for people living further north.
Light exposure helps regulate our biological and metabolic processes, so changes in the amount of light we are exposed to can disrupt cycles within the body.
A reduction of light exposure in the autumn can also lead to a potential vitamin D deficiency, which can trigger mental health problems.
Dr Kelu said: 'Given people see less light after work (when the clocks go back), this really has an impact on mood, especially for people with mood disorders.'
He said switching to one time zone would ensure maximum light exposure in the mornings and prevent our sleep from being delayed by lighter evenings.
Molecular biologist Dr John O'Neill said that because circadian rhythms are not exact 24–hour cycles, people can cope with slight delays to their cycle without any major consequences.
However, he said changes can still be disruptive and may be linked to an increase in road traffic accidents and heart attacks when the clocks change.
Dr O'Neill said Daylight Saving Time should 'absolutely' be abolished, adding: 'It's completely ridiculous that we're still living with this anachronism.'
Dr Megan Crawford sits on the executive team at the British Sleep Society, which has called for the twice–yearly clock change to be abolished and replaced by Standard Time (equivalent to Greenwich Mean Time).
She said the impact of poor sleep goes beyond disrupting our physical health and biological processes.
Dr Crawford said: 'Sleep and mental health are incredibly interlinked. Poor sleep predicts a development of things like depression and anxiety, so it has an impact on our mental health too.'
According to new analysis by The Electric Car Scheme, certain hours experience dramatic increases in crash rates immediately following the changing of the clocks.
The study examined crash data from the Department for Transport between January 2019 and December 2024, comparing the week before and after the clocks change.
Tuesday at 2am sees the highest increase in road crashes, they found, with a 300 per cent spike in accidents.
Meanwhile the hour after midnight on Sunday – immediately after the clocks go back – shows the second highest risk with 186 per cent more crashes.
Dr Thomas Upton, Clinical Research Fellow in Automated Sampling at the University of Bristol, said: 'Evidence is growing that daylight savings may be harmful to health.
'The effect of changing the clocks is a sudden change in sleep patterns. Our biological rhythms of hormones, including the hormone cortisol, keep anticipating the 'old' time and therefore get out of sync.
There is also evidence of an increased risk of cardiovascular events, increased risk of suicidal behaviours and increased mortality in the days after switching our clocks (stock image)
'There is evidence that this might contribute to worsening health including depression and even heart attacks.'
While many will be looking forward to getting an extra hour in bed Melanie de Lange, research associate at the University of Bristol, said it's unlikely you'll be able to fully take advantage.
'We analysed sleep data from activity monitors worn by 11,800 UK Biobank participants over the Spring and Autumn clock changes in 2013–2015,' she said.
'We found that people slept around an hour less on the Sunday of the Spring clock change than the previous and subsequent Sundays.
'However, they did not – or could not – take advantage of the full extra hour of sleep in Autumn. In fact, they only slept for just over half an hour more than surrounding Sundays.
'This is probably because people continue to be woken up by their internal body clock, or by children or pets who don't realise – or care – that the clocks have changed.'
How daylight saving time impacts your health
It's estimated that Americans sleep approximately 40 minutes less than usual on the Sunday to Monday night following the daylight saving time switch.
It generally takes a few days for the human body to adapt to the time change in a way that allows people to fall asleep at their typical time.
A study shows that the time change predicts a 5 percent increased incidence of heart attacks.
An experiment conducted by Professor David Wagner from the University of Oregon found that the day following the shift to daylight saving time, or following a night of sleep deprivation, people were less able to discern when a situation involved issues of moral relevance than when they were well rested.
A recent study found that judges hand out harsher sentences — 5 percent longer in duration — the Monday following the time change, as compared to other days of the year.
