The annual October clock change heralds an increase of around 20 road crashes per day in which someone is hurt, according to new research.
Analysis of police data from the past six years shows that in the two weeks after the clocks go back one hour there are an average of 278 more personal injury collisions than in the previous two weeks.
Three quarters of the extra collisions occur in the afternoons, which are darker after the clock change.
The work by the RAC Foundation – which uses methodology developed by Road Safety Analysis in 2010 – suggests that worsening weather at this time of year could also be a significant factor.
The number of collisions where someone is hurt and the weather is reported to have been “adverse” rises by a similar proportion to the overall increase in personal injury collisions, though police will not necessarily have recorded poor weather itself as a contributory factor.
RAC Foundation director Steve Gooding said: “Every year at about this time there are calls to abandon the spring forward, fall-back rhythm of daylight saving time, but our work suggests that it’s darker days and winter weather together that cause the spike in road safety risk.
“Rain, snow, ice, wind, mist and fog are all factors which make driving more challenging and – the data suggests – more dangerous.
“Wrapped up snugly in our warm and comfortable cars it’s easy to feel immune to the conditions outside, yet year in, year out, they take their toll on thousands of road users.”
The AA warned that thousands of cars with defective lights will present a greater hazard once the clocks change.
George Flinton, AA Patrol of the Year, said: “During the lighter summer months a lot of people ignore or simply don’t notice problems with their car’s lights.
“When the clocks go back in autumn, more accidents happen as cars with a blown bulb suddenly stand out in the darker evenings. It’s much more difficult for other road users to gauge how wide these cars are and they can easily be mistaken for a motorbike.”
Road safety charity Brake urged the Government to move clocks ahead all year, so winter would be one hour ahead of Greenwich Mean Time and summer would be two hours ahead.
Director of campaigns Joshua Harris said this would be a “glaringly simple and effective way to reduce deaths and injuries on our roads”.