"In industrialized countries, we view this tiredness as an intrusion, but it is the way nature intended us to feel," says David Dinges, Ph.D., chief of the psychiatry department's Division of Sleep and Chronobiology at the University of Pennsylvania School of Medicine. Chronobiologists, scientists who study the body's biological rhythms, blame our midafternoon drowsiness on the body clock, located in the hypothalamus, which also regulates such vital functions as heart rate, hormone production, and blood pressure. "The body clock, in interaction with the sleep drive, appears to produce a dip in alertness in the afternoon," explains Dinges.
Other experts link the lull more directly to body temperature, which the hypo- thalamus also controls. When body temperature decreases, many mental and cognitive skills wane as well. "Body temperature rises in the morning, peaks around noon or one o'clock, and then, in the afternoon, drops slightly," says Michael Smolensky, Ph.D., director of the Center for Chronobiology and Chronotherapeutics at Memorial Hermann Hospital in Houston and co-author of The Body Clock Guide to Better Health (Henry Holt & Company). If you alter your sleep/wake schedule, your body clock follows suit, but it takes several days. Typically, between 5 and 7 P.M. your temperature and energy peak again; from there they gradually decline, dropping you into sleep at night.
The best 6 strategies for tackling mid-afternoon malaise
Get a good night's sleep. "In our fast-paced society, most of us don't get enough rest," says Smolensky. "The combination of the body clock's biological tendency and cheating on sleep causes an increased loss of alertness in the afternoon." Though making time in our activity-crammed lives is difficult, he strongly recommends getting eight hours as often as you can.
Eat small, nutritious meals that can help combat fatigue, especially in the late afternoon. "Over and over, when I ask people who are tired in the afternoon if they ate breakfast in the morning, nine out of ten say no," says Elizabeth Somer, a registered dietician and author of Food & Mood: The Complete Guide to Eating Well and Feeling Your Best (Owl Books). She advises against carbo-loading at lunch; instead, mix protein-rich foods with carbohydrates to maximize energy. "A small turkey sandwich on whole wheat bread, a cup of low-fat yogurt, and fruit is more energizing than a plate of spaghetti," Somer says.
Get off the sugar-caffeine roller coaster. These two energy aids will give you a temporary boost, generally followed by a crash. "We have to learn to value our steady-state energy and productivity above the impulse to drink coffee or eat a Snickers bar," says Oz Garcia, author of The Balance: Your Personal Prescription for Supermetabolism, Renewed Vitality, Maximum Health, Instant Rejuvenation (Regan Books). He suggests "carbohydrate-modified snacking" on such foods as rye crackers with cheese or on protein sources like a hard-boiled egg, an energy bar, or a can of tuna.
Take a brisk walk outside after lunch. Exercise is energizing. And, Smolensky adds, "Exposure to natural light helps increase alertness."
Synchronize your tasks with your energy levels. Save demanding projects and difficult discussions for the times when your energy is high—generally not in the afternoon. "If possible, try something stimulating and interesting but not ultrademanding in the afternoon," says Thomas Lauda, Ph.D., an L.A. management coach who is writing a book about achieving and maintaining peak levels of energy at work.
Interact with people who boost your energy when your level starts to fall. "Schedule afternoon meetings with people who lift your spirits," says Lauda, "or call a true friend to talk for a few minutes."
Linda Villarosa lives in New York City and writes about health and fitness as a contributor to The New York Times.
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