Outside magazine, October 1994
It happens when you most expect it--which is when you least want it. While driving on a long road trip, taking five in the ski lodge, or working in the windowless fluorescence of your cubicle: the heavy eyelids, the wobbly neck, the dulled thoughts. Slowly, relentlessly, you start to doze.
That seemingly inevitable drift is a result of the body trying to tell time on its own terms: Each of us has an internal clock that's genetically programmed with how much sleep we require--and to keep up in the modern world, we've learned to ignore it. But in the process we've fallen farther behind in getting the rest we need. In fact, according to sleep researchers, the average young adult would sleep about two more hours each morning if the alarm didn't go off. For fitness-conscious folks the news is worse: Exercise, and the food we choose to fuel it, can make us tireder still. Yet experts in what continues to be the inexact science of sleep analysis say one solution is to heed your internal clock, while another is to avoid its signals in a number of ways. Any time-crunched athletes willing to experiment?
Technically, it's your mind that puts you to sleep. The brain sends out the signals that make you feel sleepy or wide awake, and it's a tiny bundle of brain cells called the superchiasmatic nucleus that houses your biological clock and dictates the basic rhythms of your slumber. It's also the brain, as much as the body, that needs sleep, although the theories as to why abound. "We believe that sleep reverses something harmful that builds up during wakefulness," says Scott Campbell, director of the sleep laboratory at Cornell University Medical School in Ithaca, New York. "The analogy has been used that the neural network is an interstate highway that gets a lot of daily traffic and develops potholes. Every night you have to go back and repave."
A 30-year-old's brain, as it turns out, needs about nine and a half hours of nightly roadwork, and most of us fall woefully short of getting it. The damage builds up, according to Campbell, and we all walk around in a less optimal cognitive state than if we took an afternoon nap.
Lay Off the Late Shows
Since we can't change the temperature fluctuations we're born with, sleep researchers say the best way to minimize the effects of an afternoon lull is to arm ourselves with plenty of nighttime rest. That takes regulation: Stop watching Letterman, avoid staying up late to finish a project, and don't party to all hours on the weekends. "The best thing you can do is to adjust your hours so that you wake up spontaneously," says Wilse B. Webb, professor emeritus in the psychology department at the University of Florida in Gainesville and author of Sleep, the Gentle Tyrant. "You are then getting enough rest. All you really have to do is sleep--it will tell you what the solution is."
Of course, such behavior is easier described than achieved. Most of us would rather apply Band-Aids than surgically alter our lifestyles, and sleep researchers know of a few potential ways to propel us past those bleary-eyed moments.
Look at the Light and Eat Your Beans
But as predictable an energizer as sunlight may be, carbohydrates are a surprising sleep-inducer. "If you eat a high-fat or high-carbohydrate lunch, you can be fast asleep by three o'clock," says Judith Wurtman, a research scientist in the department of brain and cognitive science at MIT. The common-sense explanation for this is that fat, and to a lesser degree carbohydrates, is hard to digest and thus uses precious energy that we need to function. But it's more complicated than that. Fat intake apparently affects peptides--small chains of amino acids--in the brain in a way that has been shown to cause lethargy, at least in animals, says Wurtman. Carbohydrates, for all their goodness in supplying a working athlete with fuel, can trigger a chemical reaction that actually starts the dozing process (see "Slow Down and Release the Insulin").
Instead, what you ought to be eating at lunch is protein. "Protein allows an amino acid called tyrosine to get into the brain," says Wurtman, "and that seems to make us alert, because it's an ingredient in two compounds that boost your mind like mental adrenaline." So lay off the spaghetti with olive oil and chocolate treats at lunch, and order a plate of rice and beans, some lowfat yogurt, a lean turkey sandwich, or a refreshing glass of skim milk.
Get Just the Right Amount of Exercise
The problem is that most of us are far beyond a neophyte's fitness plan, and the amounts of exercise we seek can undermine our ability to keep our eyes open. That's not as predictable a statement as it may seem. Remember: Much of sleepiness occurs in the mind, while a workout fatigues you physically. But go too hard and you'll find a tenuous link. "What a high level of fatigue does is make you less capable of interfering with sleep," says Webb, the psychology professor. "If we are tired, we wish to do nothing, and if we wish to do nothing, we will go to sleep." There's no exact formula for how much is too much--a marathoner is going to have a higher tolerance for duration and intensity than a casual runner--but it's not a bad idea to leave your hardest workouts for the weekends, evenings, or any time when you're not going to have to head back to a desk and try to concentrate.
Unfortunately, even if you're a cooperative but determined athlete, fatigue can come full circle and haunt you. Not only do harder workouts leave you more fatigued and hence reduce your resistance to sleep, but extremely hard workouts--or competitions--can affect you to the point that you can't get the sleep you need. "We've done studies in which a person has run a marathon and needed plenty of sleep but can't get it," says Campbell. "They're in so much muscular pain that they can't nod off."
So it all comes back to doing things in moderation. Eat the right foods, train according to a sane plan, don't use up all your daylight hours in the office, and resist cutting your sleep short. To think of sleep as time lost is exactly the wrong mentality. It's awakeness gained.
Mark Jannot, a frequent contributor to Bodywork, wrote about kinesthetics in the September issue.