The sleep cure

| January 01, 2007

Staying alert on the road requires solid rest – not gimmicks or caffeine.

What’s keeping you up at 3 a.m.? According to sleep scientists, not much.

Drowsy driving is the primary culprit in a significant number of the more than 5,000 commercial truck crashes that happen on average each year, though estimates vary widely on just how many.

Tanker hauler Danny Fox averages a good eight hours sleep a night – or day. “Sometimes you may well be on days,” he says, “sometimes you’re on nights. Then sometimes you’ll be on afternoons.” Occasionally the Airgas Southwest driver will be looking at less time asleep, though, as straight daytime sleep he finds hardest to get through. Sleep scientists say this is natural. As Fox puts it, “You’re supposed to sleep at night.”

Fifty-year-old cattle-hauling owner-operator David Conannon, of Liberal, Kan., was known to push himself to the limit in the old days. He takes it a little easier, now, he says, but he’ll still pull a trailer full of bulls through a long night. He often drinks low-sugar energy drinks to keep himself alert. “They don’t have a lot of caffeine or sugar, though,” he says. “They don’t really work if you wait till you’re really tired to drink ‘em. You have to be steady with it, set yourself.”

In a pinch, he says, “power naps work even better. If it gets bad, I’ll get off at an exit, find a place I can stop and lay down for about 30 minutes.”

A nap’s a good choice because “sleeping is the most effective way to reduce sleepiness,” as a 1997 National Highway Transportation and Safety Administration report bluntly puts it. That report also identified over-the-road truckers, among other workers with irregular schedules, as one of three highest-risk groups.

How we understand drowsiness, or sleepiness, has changed in recent decades. People still use the words “fatigue” and “inattention” when talking about drowsiness behind the wheel, but as the NHTSA report makes clear, fatigue is more accurately defined as a specific desire to not continue the task at hand, whatever the task may be. And inattention is a by-product of drowsiness, not equivalent to it. Sleepiness, scientists have shown, is altogether different.

“Sleep is not something you can automatically do well,” says Dr. Allan I. Pack, director of the Division of Sleep Medicine at the University of Pennsylvania’s Center for Sleep and Respiratory Neurobiology.

What he means, partly, is that sleep is something our bodies drive us toward – the need for sleep is controlled by processes that go on below the level of our waking minds. The daily rhythms of the body are controlled by the circadian pacemaker, a group of cells within the suprachiasmatic nucleus in the hypothalamus region of the brain, and there are particular times during the day when it’s easier or harder to sleep.

Dr. Pack describes the pacemaker as a clock with two primary functions. “One is it controls the timing of sleep,” he says, “and it also gives out a time-varying alertness signal across the day.”

The times when it’s keeping you most alert vary from person to person, but it’s during these times that it’s a really bad idea to sleep. In a person on a “normal” sleep schedule the high alertness times might correspond to mid-morning, 8 to 10 or so, and “from 5 to about 8,” Pack says. “That’s considered by sleep scientists the absolute worst time to sleep because the clock is making you so alert at that time that you have real difficulty sleeping.

“Night shift workers who sleep during the day have poorer quality sleep and do not sleep as long as those of us who work by day and sleep at night.”

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