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Staying on Summer Time 'Could Save Lives'

It may seem a long way off to us now in the middle of June, but the last Sunday in October when the clocks go back one hour is an unwelcome milestone for many people on the road to colder days and darker nights.

In parallel, the risk of being involved in a road accident increases, according to new research by the University of Surrey that confirms what road safety organisations have been saying for decades.

Researchers analysed how variations in daylight due to clock time switches affected road safety as measured by the count of daily vehicle crashes, using national data from Greece covering the ten years from 2006 to 2016. These reports, often completed by police officers inspecting crashes, included information on the date, time, location, type, and severity (fatal, serious, or minor) of accidents.

Dramatic Reduction in Serious Accidents on Summer Time

The study, published in the journal Health Economics, found "a dramatic 15-20% reduction in serious road accidents" during the spring transition to summer time, called Daylight Savings Time (DST) in Greece. Analogously, leaving DST in the autumn was associated with a 13% increase in minor road accidents.

The researchers said that the spring reduction was driven by fewer accidents occurring between 6 pm and 9 pm, because drivers had an hour more of sunlight. Conversely the increased accident rate over the transition back to standard time in the winter was mainly due to more minor accidents happening between 3 pm and 6 pm, after an hour of sunlight had been 'reallocated' back to the morning.

The authors said their estimates "support an ambient light mechanism that reduces the counts of serious vehicle accidents during the spring transition and increases the count of minor ones during the fall transition. The effects are driven from the hour intervals that are mostly affected from seasonal clock changes."

The team also conducted an economic analysis of the financial cost of these accidents during seasonal clock changes, using insurance claims data from the Hellenic Association of Insurance Companies. They estimated an average extra annual cost of nearly €1.59 million for insurance claims alone attributable to the transitions. In addition, they pointed out, vehicle accidents "may have serious implications on health, healthcare and other services utilisation, productivity, and foregone hours of work and personal time".

Extra Hour of Sunlight 'a Cost-effective Lifesaver'

The researchers concluded that fewer road accidents occur during summer time, and that "Daylight Saving Time saves lives and could save money".

Co-author Dr Giuseppe Moscelli, associate professor in economics at the University of Surrey, explained: "Not transitioning back to Standard Time in the autumn and keeping that extra hour of sunlight appears not only to be a lifesaver, but cost-effective for the taxpayer." 

The team also drew attention to similar UK-based evidence suggesting that collision risk reduces when entering British Summer Time (BST, equivalent to the European DST) and increases when exiting it. "Darker environments increase year-round road safety costs in Great Britain, due to a positive, but weak, impact on fatal accidents when entering DST in Spring," they said.

'Unnecessary' Autumn Clock Change has a Host of Negative Impacts

The Royal Society for the Prevention of Accidents (RoSPA) has campaigned for many years to end the " unnecessary" clock change in the UK, and calls on the Government instead to keep BST all year round. 

It said: "Every autumn when the clocks go back and sunset suddenly occurs earlier in the day, there is a host of negative impacts on the way we live our lives." Every year there is a trend of increased road casualties at this time, "with the effects being worse for the most vulnerable road users like children, older people, cyclists and motorcyclists".

Recent research by the RAC Foundation showed a 19% increase in road traffic collisions in the fortnight after putting the clocks back one hour from BST to Greenwich Mean Time (GMT) in the autumn, and a corresponding 11% reduction when the clocks go forward onto BST in the spring.

RoSPA also highlighted that the transition back to GMT represents an effective curfew on social activities, particularly for older generations. "Although we have more light in the mornings, this occurs when many of us are either still in bed, or indoors getting ready for work or school. That means that we have less usable daylight in the evenings to do the things we enjoy in the outdoors or in social environments." 

As well as accidents, campaigners have argued that GMT has numerous other deleterious effects including:

  • Reduced evening daylight with less ability to spend time and money on activites and socialising has knock on effects on hospitality and leisure businesses
  • Significant impacts on health and wellbeing, including conditions such as seasonal affective disorder
  • Many people being nervous about being out in the dark, leading to social isolation
  • Increased energy and fuel costs due to spending more evening time in the dark

"Given the choice, 59% of British people would prefer British Summer Time all year", RoSPA said.


The authors have no competing interests to declare that are relevant to the content of this article.