Famous Last Words: Are you sure this thing isn’t loaded?

August 28, 1996

By Wallace Immen

Medical Reporter

HOW long can you go without sleep before becoming a menace to yourself and the people around you?

The answer varies, of course, but here’s what military researchers have found:

• Deprived of sleep for 48 hours, soldiers find their ability to perform precise tasks has been reduced by 60 per cent. Marksmen literally can’t hit the side of a barn.

• After three days, the capacity to react and make decisions is less than one-quarter what it normally is. Gulf War tank crews denied sleep during the 100-hour push into Iraq began to mistake friend for foe and aim in the wrong direction.

• And four days? Actually, it’s difficult to stay awake that long because the higher functions of the brain drop to such low levels that any activity becomes the equivalent of sleep walking. You soon doze off in spite of yourself.

Why all this happens was revealed in tests that record the amount of glucose being taken in by brain cells, indicating more activity in that area of the brain.

Lack of sleep hits the thalamus first. This is the central region of the brain–its information switch. As well as being responsible for sorting out all the information delivered by the senses and the activity of muscles and nerves, the thalamus holds the key to the brain’s memory bank.

Within 24 hours, the reduction in brain function extends to the prefrontal cortex, an area near the front of the cranium responsible for learning, judgment and abstract reasoning. Because it is also a link to the brain’s emotional system, a slowdown here can make people irritable and jumpy.

Long hours without sleep also progressively shut down activity in the anterior cingulate gyrus, which processes emotions and reactions. Like people whose gyrus has been damaged in an accident, those who have gone sleepless for three days lack willpower and become reluctant to act.

Taken together, says Gregory Belenky of the U.S. Army Sleep Management System, “those are the places you’d hit, if you wanted to do a surgical strike on your work and reasoning ability.”

He was one of the U.S. military sleep researchers who were in Toronto recently to present their findings to the annual meeting of the American Psychological Association. Their visit afforded civilians some rare insight into both the effects of sleep loss and how the military hopes to ensure that modern troops required to jet half way around the world are in fighting trim once they get there.

The insight is rare, if only because scientists working for the military are allowed to subject their “volunteers” to tests that go far beyond what can be done using civilian subjects.

There may be a good reason for this. For example, you may think you’ve experienced jet lag, but consider what a bomber pilot of the future is facing. If there is another war in the Middle East, bombing runs may start in the U.S. Midwest, forcing crews to remain alert and able to execute precise manoeuvres on non-stop round-trip flights that last 36 hours.

And the research has shown that, of all the hurdles that face the attempt to push the “human envelope,” the biggest is, indeed, sleep. Fatigued muscles can recover with just a few minutes of rest, but it takes hours of slumber to restore an over-extended brain to peak performance.

Still, some of the strategies the military has devised to sustain mental prowess may help civilians get through long plane trips or all-night study sessions.

First, there is good news for workaholics: you really can catch up on the weekend. The army study found that even after staying awake for 48 hours straight, the brain can recover more than 80 per cent of its agility with just eight hours of sleep.

Other studies have shown that naps as brief as 20 minutes can significantly stave off mental fatigue. Which is why the tight cockpits of B-1 bombers are now equipped with a “gutter”–a space just long enough to let one person stretch out.

The sleep that crew members can manage during a flight is of “poor quality,” because of the noise and discomfort. Yet, even 30 continuous minutes of shuteye was enough to restore their ability to do complex tasks like flying in formation with another plane close enough to refuel, says Jon French of the U.S. Air Force Armstrong Laboratory in Texas.

One key finding of the air force studies is that the body’s natural rhythms can be used to military advantage.

Humans have evolved to be at their most active during daylight. When it’s dark, the pineal gland releases melatonin, the hormone that makes you sleepy. Mental activity slows and hits a nadir at about 4 in the morning even if you’re awake. Army tests have found that soldiers whose body time told them it was the middle of the night were much less able to perform skills like aiming weapons and that commanders took longer to make decisions.

That’s why in simulations of globe-girdling missions, B-1 bomber crews time their takeoffs from the United States so that they reach their foreign target when the enemy’s biorhythms are at their low point and, at least in theory, their own are high–their body clocks would be about 6 p.m.

As well as taking advantage of the body’s clock, the military is interested in resetting it. Researchers have been impressed by the powers of the melatonin supplement.

In tests on soldiers at the U.S. Army Aeromedical Research Laboratory in Alabama, pills containing five to 10 milligrams of melatonin produced an immediate desire to go to sleep with no side effects.

These doses are larger than the 0.3 to 3 milligrams contained in supplements sold over the counter. Those who took melatonin were more alert and accurate during tests. They also were able to avoid waking the middle of the night and averaged more sleep than people taking placebos.

Perhaps this is why even the milder melatonin has become such a fad in the United States. The supplement has not been approved for sale here, but it can be brought into the country and Canadians regularly stock up when travelling south of the border. Perhaps Health Canada will take note.

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When my knee hurts I blame Adam for his sin bringing the curse on all creation. But then I consider my own sin and I don’t have any room left to blame Adam.