Sometimes it can be tough to get enough sleep. In fact, a recent National Sleep Foundation poll found that a staggering 84% of adults admitted feeling tired during the week—mainly because they don't sleep well, or they aren't getting enough hours of shut-eye period. Beyond feeling more alert, there are a slew of health benefits associated with getting enough rest, including supporting a healthy immune system, healthy skin and a healthy heart. However, upping your hours of sleep each night can be easier said than done.
Lucky for us, researchers have identified specific micronutrients and other substances in food that show promise for the tired and weary among us. "The more interesting studies are in people who have some kind of sleep complaint, but not an actual disorder," says Michael Grandner, Ph.D., director of the Sleep and Health Research Program at the University of Arizona in Tucson, who studies nutrition's influence on sleep. "They show that you can somewhat normalize or at least make sleep better. It's hard to draw firm conclusions, but they are proof of concept." Read on for five nutrients that can help you catch more zzz's at night.
You may be familiar with the supplement form of this sleep hormone. However, it's also found in foods and is produced naturally by the brain's pineal gland. Melatonin isn't a sedative that conks you out like Ambien. Rather, it's one of the key hormones that regulates your circadian clock—an internal timekeeper of sorts that, among other things, tells you when it's time to power down and wake up. Marie-Pierre St-Onge, Ph.D., an associate professor of nutritional medicine at Columbia University and director of Columbia's Irving Medical Center Sleep Center of Excellence, explains that melatonin levels are highest during the night, drop off in the morning (daylight suppresses its secretion), and then start to rise in the evening, a few hours before sleep onset.
Your body makes melatonin from an amino acid called tryptophan found in foods (turkey is an infamous one), but plenty of dietary staples—tomatoes, oats, milk—contain straight-up melatonin. "I've come to the realization that all whole foods may have some level of melatonin. It's intrinsic to the fruits, vegetables and animal products we consume," says St-Onge. "What we don't know is how much foods actually contain." (Supplement dosages typically start at 0.5 mg.) That's because research has found that amounts of melatonin can differ greatly even among the same type of food, depending on factors such as how a plant is grown and even when a cow is milked. (Fun fact: Milk melatonin concentrations have been found to be highest when cows are milked at night.) However, there's some evidence that plant sources tend to have higher concentrations of melatonin than animal ones—and it's been shown that people who eat the most fruits and vegetables have greater amounts of melatonin in their bodies than those consuming the least. Grandner says this may be part of the reason why those adhering to Mediterranean diets sleep better than people who follow a more Western-style way of eating that's higher in refined carbs and saturated fat and lower in produce, though he notes that this hypothesis has not been well-tested.
While healthy adults usually produce enough melatonin on their own, dietary sources can give you an extra boost in the sleep department. For example, there's good research that suggests taking melatonin (most trials focus on supplements) benefits shift workers and people with jet lag, although studies on those with insomnia (chronic trouble falling to sleep or staying asleep) have been mixed. "It doesn't seem to be an effective treatment for insomnia, because for most of these people, their body knows it's nighttime, they just can't slow their minds down," says Grandner. "But there is quite a lot of data out there that shows melatonin can improve sleep health in people who just have disruptive sleep—that it can help them fall asleep faster and make sleep less fragmented." For example, a meta-analysis of 17 studies published in the journal Sleep Medicine Reviews found that, on average, ingesting melatonin helped participants with trouble sleeping nod off faster, increased total sleep time by as much as 25 minutes, and significantly improved sleep efficiency (a fancy term for the amount of time you're zonked out, minus any tossing and turning).
The hormone—which also has powerful antioxidant, anti-inflammatory and immune-bolstering properties—maybe particularly helpful for older adults, according to clinical trials. Grandner says that's because as you age, changes occur in your circadian rhythms, and levels of melatonin in the body naturally decline—a big reason why this group often has more sleep issues.
Food sources of melatonin:
Grapes, strawberries and tart cherries
Tomatoes, peppers and mushrooms
Nuts (especially pistachios and walnuts)
Barley, rice and oats
2. Omega-3 Fatty Acids
Numerous studies have noted an association between the consumption of this healthy fat—found in fatty fish (like salmon), walnuts, avocados and flaxseeds—and improved sleep quality and duration. And because your body can't produce omega-3s on its own, diet (either food or a supplement) is your only delivery system for it.
Results of a randomized controlled trial published this year in the journal Nutrients found that participants given supplements containing omega-3s nodded off faster and slept longer than those who got a placebo. This study looked at two types of omega-3s—DHA and EPA— that are mainly found in animal sources of food, but there's evidence that a variety in plants called ALA is also beneficial. And in a University of Oxford study, children given 600 mg of DHA daily for 16 weeks got nearly an hour more sleep and had seven fewer nighttime awakenings, on average, than they did before the trial. (For comparison, 3 ounces of salmon has about 1,000 mg of DHA.)
While some studies use supplements with doses higher than what you may get via fish or nuts, research does show that people with the most omega-3s in their diets have healthier sleep patterns than those who eat the least.
What makes omega-3s such good bedfellows? "We know that they help with circadian timing. And they reduce inflammation the body, which has been linked to better sleep," says Michael Breus, Ph.D, fellow of the American Academy of Sleep Medicine. Fatty fish may be a particularly good sleep aid. It offers a trifecta of benefits: in addition to the omega-3s, it also contains vitamin D (more on that below) and tryptophan, which your body converts to melatonin.
Food sources of omega-3 fatty acids:
Seafood (especially salmon, tuna and sardine)
3. Vitamin D
"Vitamin D is one of the circadian pacemakers—it keeps your sleep-wake cycles aligned and working nicely," says Breus. Yet around 40% of American adults are deficient. (Less than 12 ng/mL—nanograms per milliliter—is considered a deficiency; 12 to 20 ng/mL is an inadequacy.) A meta-analysis of studies with more than 9,300 participants, published in the journal Nutrients, found that low blood serum levels of vitamin D—less than 20 ng/mL—were associated with poor sleep, fewer hours of zzz's and daytime drowsiness. And a trial that measured the sleep patterns of more than 3,000 older men, published in the journal Sleep, showed that participants with low vitamin D had poorer quality and quantity of rest than those with adequate levels. The researchers note that the findings "suggest a potential role for vitamin D in maintaining healthy sleep." There's evidence that lack of vitamin D may up the risk for sleep apnea, as well. You can get vitamin D from some foods, including fatty fish, such as salmon, and fortified cereal and dairy products. But there's a reason it's called the "sunshine vitamin": between 50% and 90% of your vitamin D comes from UV exposure. Around 15 to 20 minutes of direct sunlight on your skin causes your body to produce what you need. So in addition to diet, Breus recommends spending 15 minutes outside daily, sans sunglasses—your eyes can also synthesize the vitamin—or SPF. (Long enough to get a dose of D without getting burned.) And because deficiencies are so common, it's not a bad idea to get your levels checked. It's a simple blood test your doctor can order. If yours are low, you may want to consider taking a supplement as an insurance policy.
Food sources of vitamin D:
Trout and salmon
Vitamin-D-fortified foods like cereal and plant-based milks
According to the National Institutes of Health, 48% of Americans get too little of this mineral. (RDAs for adults range from 310 to 420 mg.) And that does not bode well for sleep. For starters, magnesium deficiency has been linked to an uptick in mood disorders, such as depression and anxiety, which are proven snooze annihilators. "Magnesium calms you down," Breus explains. "It's an anxiolytic—a substance that prevents and treats anxiety—so it helps you relax and allow the natural sleep process to take over." Plus, it's involved with the regulation of your circadian rhythms. In a study of older adults (age is a risk factor for low magnesium), those given 500 mg of the mineral daily for eight weeks dozed off 12 minutes faster, stayed asleep 36 minutes longer and had fewer early morning awakenings than usual. Meanwhile, a placebo group had virtually no changes in their sleep. Boosting magnesium levels in those who are lacking is also associated with more slow-wave sleep—the "restore and recover" kind that's key for immune health and repairing muscle and other tissues in the body. Unlike vitamin D, your body doesn't make magnesium, so you have to eat it.
Food sources of magnesium:
Nuts and seeds (especially pumpkin seeds, chia seeds, cashews, peanuts and almonds)
Fortified breakfast cereals
This is yet another micronutrient that Americans tend to fall short on— particularly women. (RDAs for adults range from 8 to 27 mg.) Iron-deficiency anemia—which occurs when your body does not have enough iron to produce hemoglobin, necessary for your blood to carry oxygen—can make you feel tired in its own right, regardless of how much rest you get. But it has been tied to sleep troubles, as well. (There are several ways your doctor can assess your levels, but a common one is a ferritin blood test that measures the amount of iron stored in your body.)
This essential mineral is involved in certain chemical processes in the brain that are linked to sleep physiology. A review of studies on micronutrients and sleep that Grandner worked on found that people with iron-deficiency anemia experienced more night wakings and shorter sleep compared to people with adequate levels of iron. It was also shown to throw off their various stages of sleep. On the flip side, iron-deficient people who upped their intake to normal levels slept better and longer.
"There's also a lot of evidence that low iron levels can cause restless leg syndrome—a creepy-crawly discomfort in your legs that mostly happens at night," says Grandner. "It's a neuromuscular issue that has to do with how your brain transports iron." In fact, after controlling for other factors that might impact sleep, a Turkish study found that 68% of those with iron-deficiency anemia had problems sleeping, and another concluded that 24% suffered from restless leg syndrome—a number nine times higher than the general population.
Food sources of iron:
Legumes (especially lentils, white beans and chickpeas)