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Blink you are dead – Driver sleepiness

13 July 2009

It was 3 a.m., and John was only 30 minutes from home. He felt drowsy but was sure he could fight off the tiredness dragging at his eyelids. He turned up the music, opened his window and chewed harder on his gum. His eyes closed for only a few seconds. John died in his sleep. So did the family in the car he hit.

Sleepiness kills

They call it the silent assassin because sleepiness kills. Tiredness is a huge road safety problem. So is denial. Tired drivers cause thousands of deaths and serious injuries every year, yet even professional drivers (and their bosses) don’t always acknowledge the danger.

The Loughborough Sleep Research Centre in the UK has spent more than a decade investigating driver fatigue, analysing thousands of motorway accidents and demonstrating the true extent of the problem.

Working with, among others, the UK government, police forces and companies in the transport industry, and running special training courses for drivers and their trainers, the centre uses sophisticated software and a driving simulator. This evaluates driving behaviour and the physiological state of tired drivers using an (electroencephalogram).

Sleepy drivers cannot fight back

The video of a driver at the wheel of the red car in an office at the centre is disturbing viewing. Monitored by around 20 carefully positioned electrodes, he has to indicate his level of tiredness according to the Karolinska Sleepiness Scale (developed by the Karolinska Institute in Sweden). Level one is wide awake, nine is fighting sleep, 10 is asleep. Anything over seven is dangerous for a person driving. His long blinks are getting longer, but he shows no sign of stopping and shouts “five” when he has just driven with his eyes closed for several seconds.

Myths

In more than a decade of research and simulator tests on drivers, none of these strategies counteracted sleepiness: Opening windows Turning up the radio Chewing gum Taking a short walk Willpower Eating

Dr Louise Reyner, who has worked with the head of the centre, Professor Jim Horne, for more than 15 years, says they have proved categorically that no driver can fight sleep. Also, men are far more likely to continue driving despite drowsiness, and professional drivers can sleep with their eyes open!

Sleepy driver responsibility

The dangers of driver fatigue have only been taken into account after accidents comparatively recently. Dr Reyner explains: “It’s like the attitude to drink driving – 40 years ago if you drank and had an accident, it wasn’t your fault. We’ve been able to show that when you’re falling asleep, you know you are.”

A likely time for accidents

The sleep centre’s in-depth research started in the early 1990s with police studies of motorway accidents. Various projects have looked at sleepiness and sleep patterns in factory, ship and shift workers, and all confirm the importance of our natural body clock. Everyone suffers a dip in the early hours and mid-afternoon.

The SRC’s software is now so reliable it has been used in court cases involving tired drivers in fatal accidents.

“We have a graph of when crashes occur, and there are peaks around 2 a.m., 5-7 a.m. and 4 p.m.,” says Dr Reyner.

“Professional drivers can drive legally for 4.5 hours at a time, but if that is in the early hours they are vulnerable.”

Sleep increases road safety

She insists that any measures taken to stay awake should only be a temporary solution. One study showed that the energy drink Red Bull, with 80 mg of caffeine per can, is as, if not more, effective as a cup of coffee, which varies from 20 – 120 mg of caffeine.

“The best advice to drivers is to avoid the situation,” Dr Reyner says. “Plan rest stops before you get sleepy. Plan your journey to avoid vulnerable times. Mild to moderate sleepiness lasts 1–1.5 hours, so there’s time to react.”

The phenomenon of professional drivers sleeping with their eyes open was first discovered in 1929. The Sleep Research Centre has yet to establish a scientific explanation.

Ageing truck drivers

Dr Reyner is especially concerned about truck drivers – an ageing population because younger men are not keen on driving long distances in increasingly heavy traffic. Many drivers are also overweight, which can contribute to daytime sleepiness by causing sleep apnoea.

“There can be a problem with the soft palate, but 90 percent of cases are caused by being overweight,” she says. “They can be waking up hundreds of times a night and not know it.”

Sleepy drivers need sleep

The Src’s next studies will begin looking at the importance of motorway service stations and levels of daylight when accidents occur. But Dr Reyner says that in the long run there is no solution to driver sleepiness – apart from sleep.

“A lot of crashes involve people doing their best, working long hours and not liking to say no,” she says.

“They end up taking unnecessary risks. Whatever anybody thinks or tells you, we all require the same amount of sleep. And driving is the most dangerous thing you can do unless you go bungee jumping or skydiving. Yet we get behind the wheel without a thought.”

Driver sleepiness

• Sleepiness is the most likely cause of accidental death among truck drivers.
• Sleep-related accidents are the most likely reason for totally writing off a truck, and there’s a significant chance that all trucks will be involved in at least one sleep-related crash during their lifetime.
• Sleep-related accidents are three times more likely to result in death or serious injury.
• Sleepy drivers kill more people than drunk drivers do.
• Tiredness causes more than 20 percent of UK motorway accidents and at least 10 percent of all road accidents.
• Falling asleep at the wheel results in worse accidents involving higher speeds and less avoiding action.
• Men in particular will continue driving despite drowsiness.
• A “long blink” or microsleep can last as long as 30 seconds.
• Tired drivers over-estimate their alertness.

How to prevent tiredness

2–6 a.m.

• Follow your body clock: Most accidents happen at low points between 2-6 a.m. and 2-4 p.m.
• Get off the road, find somewhere safe to park, and take a nap.

1–2 cans

• Drink one to two cans of a high-caffeine energy drink or two cups of coffee, then nap for
  20 minutes to allow the caffeine effect to kick in.

7–8 hours

• Catnaps help but are no substitute for a good night’s sleep (seven to eight hours).
• Sleep debt built up over a series of disturbed or short nights’ sleep can be made up with two good, consecutive nights’ sleep.

Avoid alcohol

• Plan journey breaks at safe stops, taking into account long stretches of monotonous road, such as motorways, and vulnerable times.
• Listen to your body: If you feel sleepy, you need sleep.
• Rest is never a substitute for sleep.
• Avoid alcohol and medications that cause drowsiness.

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