Daylight savings sleep shift increases health risk for drivers

As daylight saving begins, Kiwis may welcome the brighter evenings and promise of summer BBQs, but the switch comes with a darker side.

Health data shows the sudden disruption to body clocks has measurable consequences: hospitals in Michigan, US found heart attacks spike by 24 percent on the Monday immediately following the spring shift, while a 2024 review of 12 studies confirmed a four percent increase in risk across the two weeks that follow setting clocks an hour forward. Road crashes also climb by around six percent in the same week, underscoring that losing even a single hour of sleep can have serious effects on both wellbeing and road safety.

Economists at the London School of Economics estimate that ending daylight saving could deliver wellbeing gains worth roughly NZ$1,400 per person annually, with the wider toll of sleep deprivation — to which clock changes contribute — costing around NZ $680 billion worldwide each year.

Katrina Aubrey, Fatigue and Sleep Specialist at AutoSense, New Zealand fleet safety experts, says the health impacts of daylight saving is often underestimated, particularly for people who drive for a living.

“Our body clocks are finely tuned. Losing up to an hour of sleep — as happens every spring — disrupts circadian rhythms and increases fatigue. This sleep deprivation also affects heart health in multiple ways. Poor sleep increases inflammation, which can damage blood vessels and increase heart disease risk, and losing sleep elevates the risk of arrhythmias – irregular heart rhythms – potentially increasing the risk of stroke and heart-related issues,” says Aubrey.

“The fatigue and disruption also affects reaction time, mood and alertness — all critical for safe driving. For professional drivers who work long hours, the impact can be especially dangerous for them, and for everyone they share the road with.”

AutoSense is working with more than 800 transport operators including NZ Post, Mainfreight and Fonterra to reduce incidents and protect drivers through training and technology. The business has installed Guardian by Seeing Machines driver safety technology in 5,969 vehicles across 864 fleets in New Zealand, with the cameras monitoring fatigue and distraction events in real time, every second of the day and night.

Using AI, the technology combines cutting-edge optics and processing to continuously monitor a driver’s eye and head movements, capable of detecting early signs of drowsiness and distraction. Fatigue events are detected when the driver’s eyes are closed for 1.5 seconds or longer when travelling at or above a set speed threshold.

The system issues real-time audio, visual and seat-vibration alerts to help drivers act before fatigue or inattention becomes critical. The technology includes another layer of safeguarding – any red-flagged video is assessed by a human ‘Guardian Angel’ in a call centre. The Guardian Angel looks for signs of fatigue or distraction, and will intervene by alerting the driver to take a rest from driving.

In the year to 31 July 2025, AutoSense says an astounding 19,390 driver fatigue events, and 52,553 distraction events were recorded by the Guardian cameras in Aotearoa.

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Source: AutoSense