The mistake South Africans make that’s even more dangerous than drunk driving

South Africans who drive tired may be ignoring one of the biggest blind spots in road safety and underestimating the dangers of getting behind the wheel after not getting enough sleep.

This is according to new research from Discovery Insure, which analysed four years of driving and sleep data.

The insurer’s data shows that missing sleep across several consecutive nights is one of the strongest predictors of motor vehicle accident risk.

It highlights an often-overlooked factor that may help to prevent future vehicle accidents from occurring.

“The research links four years of sleep data from more than 10,000 Discovery Insure drivers with their driving behaviour and accident outcomes, making it one of the largest studies of its kind conducted in South Africa,” the insurer explained.

Robert Attwell, CEO of Discovery Insure, added that while breathalysers can detect alcohol impairment – a visible and well-understood risk factor for accidents – driver fatigue, by contrast, has until now been largely invisible.

“Sleep affects concentration, reaction time and decision making, all of which directly influence driving behaviour and outcomes,” he said.

“Our research suggests that poor sleep is up to five times more predictive of motor vehicle accident risk than traditional insurance risk factors considered in isolation.”

“That points to a significant blind spot in how driving risk has traditionally been understood, both locally and globally.”

Discovery pointed out that one of the clearest findings is that it is not a single night of poor sleep that affects driving ability.

Rather, missing sleep over several consecutive nights, which is known as sleep debt, has an even greater impact on crash risk.

The data shows that nearly 30% of Discovery Insure drivers accumulate some level of sleep debt, and nearly half of sleep’s overall impact on accident risk is linked to chronic poor sleep rather than an isolated night.

Rapidly changing risks

Additionally, the research highlights that the risk can change quite quickly, as drivers who maintain less than one hour of sleep debt over three consecutive nights have a significantly lower accident risk.

According to the data, these individuals have an up to 36% lower risk of crashing than those carrying five or more hours of sleep debt over the same period.

Beyond this, Discovery’s research also found that:

• Drivers who regularly get seven to eight hours of sleep are around 32% less likely to be involved in an accident than those who sleep too little.
• Drivers who go to bed within roughly one hour of their ideal bedtime each night are up to 36% less likely to have an accident than those with irregular sleep patterns.
• Drivers who get adequate Rapid Eye Movement (REM) sleep experience around a 14% lower accident risk.

The insurer explained that despite growing evidence, many people still underestimate the dangers of driving while tired.

A 2024 survey found that around 90% of adults avoid driving when they have had a few drinks, but only 50% said they’d do the same when they had poor sleep.

Further research has also found that being awake for over 16 hours can impair driving ability as much as being above South Africa’s legal 0.05% blood alcohol limit.

Every year, road traffic accidents claim about 1.19 million lives around the world, and research suggests that driver fatigue contributes to at least one in five of these crashes.

Road crashes also cost the local economy an estimated R205 billion in 2023, which is equivalent to around 2.7% of South Africa’s GDP.

“For years, road safety efforts have rightly focused on risks like speeding, distracted driving and drinking and driving,” said Attwell.

“Our research suggests tired driving deserves the same level of public awareness because the consequences can be just as severe.”