The tiredness/drunkenness equation

Posted on December 14, 2012


South Africa now has a promised crackdown on tired drivers with officials at roadblocks instructed to pull them over and instruct them to get some sleep. How this can be done and how tiredness can be assessed is a problem, but such a move is perhaps long overdue.

Because sleep deprivation has similar effects to being drunk or having driving abilities impaired by a hefty dose of alcohol. Severe sleep deprivation does strange things to the mind, and can result in slurred speech, wandering concentration and apparent difficulty in physical co-ordination. More than a decade ago, Australian researchers showed conclusively that lack of sleep and drunkenness could be equated.

They developed a method which allows the fatigue suffered by an individual to be equated to the level of alcohol in the blood. For example, anyone awake for 21 hours has the same impaired capacity as someone with a blood/alcohol level of 0,08 per cent, in other words, well beyond the level for a drunk driving conviction in most countries.

To reach the blood/alcohol level for a local drunk driving conviction — 0.05 per cent — takes just 17 sleepless hours. There is also a cumulative effect when sleep is interrupted and when an individual stays awake for lengthy periods over several days, weeks or months.

Such an effect is a largely unrecognised cause of thousands of industrial accidents among workers forced, for one reason or another, to work long and often irregular hours. In the transport sector this scenario can contribute to particularly horrific consequences and South Africa’s annual road death toll is clear evidence of this.

Only in the air does this factor appear to be taken fully into account. Airline pilots and flight crew have a complex set of arrangements which take full account of the need to sleep.

On a long non-stop South African Airways (SAA) flight to a destination such as Miami, for example, there are two flight crews on board, one accommodated in full sleeping quarters. No individual is at the controls for longer than 8.5 hours.

“None of this is a question of dodging work; it is purely a matter of safety,” notes an SAA captain.

The same level of concern about sleep and safety does not, unfortunately, usually apply to other sectors. Even the conditions laid down in the local Basic Conditions of Employment Act are frequently observed more in the breach.

Conditions for train drivers in South Africa have improved over the past decade, but many still work long hours and back-to-back shifts. Long distance truck and taxi drivers are much less regulated, with the drivers of long distance mini-bus taxis often having to wait hours before their vehicles fill before setting off on eight and ten-hour journeys.

Long-distance coach drivers too, often work shifts of four hours behind the wheel, and four hours “resting”, often on the back seat of the coach, before doing another four hours behind the wheel.

A classic — and tragic — example of what such cumulative lack of adequate sleep can mean emerged at the 2000 hearing into a 1999 Metrorail crash in Gauteng where four passengers died and 17 were injured. Evidence showed that the driver had worked for seven days a week for months on end. In his last 14 shifts, eight had been for longer than 14 hours.

According to Dr Alison Bentley, a sleep deprivation expert from the University of Witwatersrand, in Johannesburg, the driver was suffering from extreme fatigue. Had it been liquor, rather than sleep deprivation, which had brought him to that state, he would probably have been dead from alcohol poisoning.

Unfortunately, tired drivers, like their drunken counterparts, seldom acknowledge impairment. However, education about alcohol levels and impairment has begun to make a mark. A similar education campaign is needed about sleep deprivation, because it is a perhaps more insidious danger.

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