Foods’ effect on getting sleep is inconsistent

Sleep. Oh, to sleep.

A good night’s sleep is often a struggle for more than half of American adults. And for occasional insomnia, there are good reasons to avoid using medications, whether over the counter or prescription.

We’ve all heard about home remedies such as warm milk, chamomile tea with honey, or a shot of bourbon or brandy as a nightcap. On the Internet, you can find claims about all kinds of foods that help with sleep: fish, cherries, lettuce, miso, yogurt, bananas, almonds, eggs, edamame, pineapple, jasmine rice, potatoes, cereal, to name a few. Is this just click bait for insomniacs staring at their screens at 11:30 p.m.? What does the science say?

Michael Grandner, a sleep researcher at the University of Pennsylvania, says the best way to start adjusting your diet is to eliminate foods that interfere with sleep. “The obvious one is caffeine,” he says, “but people forget about it.” They’ll drink a soda at dinner or have a cup of coffee with dessert. Caffeine typically stays in the body for four to six hours, he says, “but some people are more sensitive and the effect might last twice that long.”

Alcohol is also bad for sleep. While it may make it easier to doze off, it makes your sleep more shallow, Grandner says. “It suppresses REM sleep early in the night, which can lead to REM rebound later,” which can wake you up. Also, as alcohol is metabolized, one of its byproducts has stimulant action. Grandner also says to avoid nicotine, large meals and spicy foods at dinnertime.

Are there any foods that promote sleep? There is some science behind these supposed dietary sleep aids, but it’s piecemeal at best. For example, turkey contains tryptophan, which is a building block for serotonin, a chemical involved in sleep. But there’s nothing special about turkey, as all meat contains tryptophan — as does warm milk.

Further, tryptophan is a big molecule that has trouble crossing into the brain, so improving your sleep is not as simple as eating a tryptophan-rich food and getting more serotonin. And, serotonin has multiple functions in the brain, including some that promote wakefulness, so more serotonin does not automatically mean better sleep.

Studies that found a tryptophan effect relied on doses that would require eating a pound of meat at a sitting, Grandner says. “If you’re eating so much food to get the tryptophan effect, you might suffer the too-much-food effect.”

Other foods, most notably tart cherries, contain melatonin, which does affect sleep. Still, melatonin is not necessarily a sleep aid, says Wilfred Pigeon, a sleep researcher at the University of Rochester. “Studies show it has a very minimal impact on insomnia,” he says. “On the other hand, melatonin is a wonderful circadian rhythm shifter.”

So if you’re a night owl whose body prefers to sleep from 2 a.m. to 9 a.m. but you have to wake up at 7 a.m. every day, melatonin may help you alter your sleep schedule. Pigeon and Grandner say that to get that effect, it would be best to take melatonin at dinnertime rather than at bedtime — and that lower doses (1.5 to 3 milligrams) are better than higher ones. That allows the substance to work with your body’s internal clock, starting the long wind-down process that’s tied to sundown.

Pigeon conducted a small study with a tart cherry juice that had been developed as a sports drink. The participants — 16 elderly adults with chronic insomnia — reported less wakefulness during the night (by an average of 17 minutes) and more total sleep time (eight minutes) when they drank the juice than when they drank cherry Kool-Aid, which does not contain the melatonin and other phytonutrients found in the sports drink.

“It was not a huge effect,” Pigeon says. Indeed, the participants still had significant sleep disturbance after two weeks on the tested juice. But Pigeon says the effect was nonetheless on par with what some studies have found with the herbal supplement valerian and with melatonin in pill form.

What about other supposed remedies? Dairy is a good source of calcium, and nuts and grains contain magnesium. Miso soup, fish and yogurt contain B vitamins, such as B6.

“These are all molecules important in sleep and sleep regulation,” Grandner says.

That means that B vitamins, calcium and magnesium can be linked to some of the biochemical processes involved in sleep. But merely eating them doesn’t mean the nutrient goes directly to sleep pathways in the brain.

A comprehensive review of studies testing foods or nutrients on sleep confirms the inconsistency of food as a way to promote sleep. One study might show that milk helps sleep, but the next finds no effect. The same for chamomile tea, B6 and magnesium.

That said, sleepy-time foods don’t have any worrisome side effects. And the ritual of drinking something before bed may be conducive to sleep, Pigeon says. “Anything that is soothing or relaxing can help.”