By Rachel Johnson, Ph.D, M.P.H., R.D., March/April 2008
Unrelenting insomnia has become a part of my life. Colleagues joke about my 3 a.m. e-mails; my husband groans at my late-night online shopping. (He knows I’ve had a bad stretch when packages pile up at the door.) There are weeks when I’d give just about anything for a good night’s sleep. I also know that I’m not alone.
Fifty to 70 million Americans suffer from insomnia. It’s more common among women (I know the hot flashes keeping me awake are caused by declining estrogen and hopefully will pass as my hormones even out). It is also common among people who are obese or have high blood pressure, anxiety or depression. And more and more studies are linking weight gain with sleep loss. A new study in the Journal of Clinical Sleep Medicine suggests that adults should sleep eight to nine hours per night to help maintain a healthy weight. One theory is that lack of sleep disrupts hormones, such as leptin and insulin, which regulate appetite and body weight. Another explanation is that sleep deprivation leaves us too tired for exercise. And since losing sleep can also make us moody, we may turn to food to cheer us up.
I could take one of the many sleep medications touted on TV, but I’d rather not; their long-term use can lead to headaches and possible dependency. Instead, I’m channeling my late-night energy into researching the science behind some common advice.
Decades ago, scientists looked into this folk remedy and posited that tryptophan, an amino acid in milk (and turkey), might be responsible for its supposed sleep-inducing effects. Earlier research had shown that when tryptophan is released into the brain, it produces serotonin—a serenity-boosting neurotransmitter. But when milk (and other tryptophan-rich foods) were tested, they failed to affect sleep patterns. “Tryptophan-containing foods don’t produce the hypnotic effects pure tryptophan does, because other amino acids in those foods compete to get into the brain,” explains Art Spielman, M.D., an insomnia expert and professor of psychology at the City University of New York. Warm milk at bedtime may be comforting, but it won’t boost sleep-promoting serotonin.
A light bedtime snack can stave off hunger, a known sleep robber. But eating high-glycemic-index (GI) carbohydrates—hours earlier at dinner—might also help. (High-GI foods cause a greater rise in blood sugar and insulin than do lower-GI foods.) A recent paper in the American Journal of Clinical Nutrition found that when healthy sleepers ate carbohydrate-rich suppers of veggies and tomato sauce over rice, they fell asleep significantly faster at bedtime if the meal included high-GI jasmine rice rather than lower-GI long-grain rice. While the authors aren’t sure how it happened, they speculated that the greater amounts of insulin triggered by the high-GI meals increased the ratio of tryptophan relative to other amino acids in the blood, allowing proportionately more to get into the brain. Save high-GI carbs for dinnertime, when their side effect—drowsiness—is a plus.
Chamomile, lemon balm, hops and passionflower are all touted for their sleep-promoting properties. You’ll often find them in “sleep-formula” tea blends, but unfortunately their effectiveness hasn’t been proven in clinical studies, according to the American Academy of Sleep Medicine. “I don’t doubt these teas work for some. A warm liquid before bed may produce sleepiness by generating body heat,” speculates Spielman. Beware: drinking liquids close to bedtime can mean nocturnal trips to the bathroom. A cup of “sleep-time” tea might be worth a try…if you have a strong bladder.
Shelves in supplement stores are stacked with sleep formulas. According to one NIH survey conducted in 2002, 1.6 million people tried complementary or alternative therapies like these, and over half of them reported their insomnia improved “a great deal.” However, those glowing anecdotes haven’t been backed up by rigorous scientific study; evaluations of most nutritional supplements haven’t shown any effects whatsoever. The one exception is valerian root, which seemed to help improve sleep with rare, and mild, side effects, such as stomach upset. But finding an effective formulation of valerian root is tricky, since the FDA doesn’t regulate herbal supplements. Don’t waste your money on sleep supplements; hold off on using valerian until standardized formulations become available.
Though a glass of wine may help you fall asleep, excessive alcohol use can make you wake up in the night. One theory is that alcohol suppresses the REM (rapid eye movement) sleep state that’s critical to a good night’s sleep, says Spielman. “One of my insomnia patients became remarkably better when he reduced his alcohol intake from 20 to three drinks per week.” Drink moderately, if at all; avoid drinking within a few hours of bedtime.
Caffeine affects everyone differently, so if you’re sensitive it might be worth trying to cut down—or limit caffeine to the morning only. This can mean more than just cutting out a cup of coffee. The major sources of caffeine in Americans’ diets are coffee (71 percent), soft drinks (16 percent) and teas (12 percent) but chocolate is also a source. “Our ability to excrete caffeine decreases with age,” says Spielman, so while you might have tolerated four cups of coffee a day when you were 20, you’ll probably need to cut down as you get older. Cut down on caffeine or limit it to the morning; if insomnia persists, consider going cold turkey.
I’m going to try all of the above advice in my quest for shuteye. I know enough about the placebo effect to be content with just believing it will work. As for my husband he’ll be content—no, grateful—if my nighttime shopping tapers off.
Rachel Johnson, EatingWell’s senior nutrition advisor, is dean of the University of Vermont College of Agriculture & Life Sciences.