To Sleep Better, Change What—and When

Did your mum ever suggest a warm glass of milk to help you sleep?

Science says she may be right.

An emerging field of research called chrononutrition indicates that choosing the right foods and meal times may improve our sleep . Some key findings: Eat dinner early. Keep consistent schedules. And, yes, drink milk.

You already know that fruits, veggies and lean protein are good for your health. But they can boost your sleep, too. These foods are the basis for the Mediterranean diet, which research shows may improve sleep quality, reduce sleep disturbances and boost sleep efficiency—the amount of time you spend asleep when you are in bed.

Eating a Mediterranean or other similarly healthy diet is linked to a reduction in symptoms of insomnia , according to a just-published review of 37 studies with almost 600,000 participants. This same research also found that unhealthy diets—high in simple carbohydrates and processed foods —are associated with an increase in insomnia symptoms, says Frank Scheer, a professor at Harvard Medical School, who studies the internal body clock.

When we eat affects our internal body clock, or circadian system, which regulates our physiology and behaviour, including sleep. While our master clock resides in our brain, each of our organs has its own clock, too. We don’t want to wake up our stomach just when we’re trying to go to sleep.

“There’s a rhythm to our digestive system,” says Kelly Baron, director of the behavioural sleep medicine program at the University of Utah. “And eating at the wrong time can cause internal jet lag.”

Roughly a third of American adults don’t get the recommended seven to nine hours of sleep, according to the Centers for Disease Control and Prevention.

When Sarah Linderman, 46, started having sleep problems several years ago—tossing and turning for hours before drifting off, then popping awake for good at 3 am — a doctor suggested she focus on her diet.

The doctor recommended she consume more of her calories earlier in the day, load up on protein and veggies, cut back on cocktails at night and finish her last meal at least three hours before bedtime. Linderman soon found herself falling asleep more easily. She also began sleeping seven or eight hours uninterrupted and waking feeling refreshed in the morning.

“With the right nutrition, I took my sleep back,” says Linderman, who owns a marketing company in San Pedro, Calif.

What’s the best way to adjust your diet to improve your sleep? Here’s some advice, according to a growing body of research.

Follow a Mediterranean diet

A diet high in vegetables, fruits, whole grains, fish and unprocessed lean meat is good for nutrition and may promote sleep by reducing inflammation and providing nutrients that boost the neurotransmitter serotonin and the hormone melatonin. It also balances our gut microbiome , which may help regulate our circadian rhythm, says Uma Naidoo, a nutritional psychiatrist and director of nutritional, lifestyle and metabolic psychiatry at Boston’s Massachusetts General Hospital.

Some nutrients are particularly helpful.

Tryptophan is an amino acid necessary to produce melatonin. Our bodies can’t produce tryptophan, but foods that provide it include turkey, chickpeas, milk, grains, nuts and seeds.

Serotonin is also a precursor to melatonin. Fruits, vegetables and nuts can help boost serotonin.

Melatonin promotes sleep and influences the timing of the circadian system. Eggs, fatty fish such as salmon, mushrooms, bananas and tart cherries help promote it.

Naidoo’s perfect sleep-promoting dinner suggestion? A mushroom omelet with a side salad topped with flaxseed and walnuts.

Have an early dinner

People who eat close to bedtime have poorer sleep quality, studies show.

Researchers think this may have something to do, in part, with body temperature. Our body typically cools down before bed; this is an important part of our circadian rhythm. Digestion heats our body up, messing with this process.

“Your stomach is working up a sweat just as you’re trying to wind down,” says Marie-Pierre St-Onge, director of the Center of Excellence for Sleep and Circadian Research at Columbia University.

Eating before bed can also cause acid reflux, which often disrupts sleep.

A good rule of thumb, researchers say: Eat dinner at least two to three hours before bedtime to give yourself time to digest your meal.

Be consistent about meal times

Having a regular eating rhythm sends a strong signal to your brain about when it is time to be alert and when it is time to be drowsy, says the University of Utah’s Baron.

Try to eat your first meal and your last meal around the same time each day. “This bookends your day and helps differentiate between waking activities and nighttime,” Baron says.

Eat breakfast

When we don’t eat breakfast, we tend to get hungrier at night. And that sets us up for making poorer food choices closer to bedtime, says St-Onge.

Some studies have shown that people who skip breakfast have lower sleep quality. Researchers aren’t sure why, but they believe it’s because people who eat breakfast tend to practice other healthy habits, such as being more active.

Cut back on alcohol

Yes, alcohol may help you wind down at night and fall asleep faster. But it also messes with your sleep quality . (Do I really need to tell you this?) It suppresses REM sleep, causes sleep disturbances and shortens sleep duration, says Massachusetts General’s Naidoo.

A light evening snack is OK

Hunger is stimulating because the hormones that make you seek food are the same ones that arouse you from sleep, says Columbia’s St-Onge. It’s hard to fall asleep when you’re obsessing about the ice cream in your freezer.

If you eat a snack, make it light and have it at least an hour or so before bed. Pair protein and healthy carbohydrates—hummus and pita or fruit and yogurt—for the biggest sleep boost. Protein is satiating and carbohydrates promote sleepiness by helping the absorption of tryptophan.

And, yes, milk can help, too. A study of people recovering from a cardiovascular event showed that they slept better if they drank milk with honey before bed. And, in general, people who consume more milk throughout the day have better sleep, research shows. Milk is a good source of tryptophan, St-Onge says.

So go ahead and listen to your mum. Have that glass of milk.

Must even steak be politicised? The American Heart Association recently recommended eating more “plant-based” protein in a move to counter the Health and Human Services Department’s new guidelines calling for more red meat.

Few would argue that eating a Big Mac a day is good for you.

On the other hand, growing evidence, including a study last month in the Journal of the American Medical Association, suggests that eating more meat—particularly unprocessed red meat—can reduce the risk of Alzheimer’s in the quarter or so of people with a particular genetic predisposition.

The APOE4 gene variant is one of the biggest risk factors for Alzheimer’s.

You inherit one copy of the APOE gene from each parent. The most common variant is APOE3; the least is APOE2.

The latter carries a lower risk of Alzheimer’s, while the former is neutral. A quarter of people carry one copy of the APOE4 variant, and about 2% carry two.

APOE4 is more common among people with Northern European and African ancestry. In Europe the variant increases with latitude, and is present in as many as 27% of people in northern countries versus 4% in southern ones. God smiled on the Italians and Greeks.

For unknown reasons, the APOE4 variant increases the risk of Alzheimer’s far more for women than men.

Women’s risk multiplies roughly fourfold if they have one copy and tenfold if they have two. Men with a single copy show little if any higher risk, while those with two face four times the risk.

What makes APOE4 so pernicious? Scientists don’t know exactly, but the variant is also associated with higher cholesterol levels—even among thin people who eat healthily.

Scientists have found that cholesterol builds up in brain cells of APOE4 carriers, which can disrupt communications between neurons and generate amyloid plaque, an Alzheimer’s hallmark.

The Heart Association’s recommendation to eat less red meat may be sound advice for people with high cholesterol caused by indulgent diets.

But a diet high in red meat may be better for the brains of APOE4 carriers.

In the JAMA study, researchers at Sweden’s Karolinska Institute examined how diet, particularly meat consumption, affects dementia risk among seniors with the different APOE variants.

Higher consumption of meat, especially unprocessed red meat, was associated with significantly lower dementia risk for APOE4 carriers.

APOE4 carriers who consumed the most meat—the equivalent of 4.5 ounces a day—were no more likely to develop dementia than noncarriers. (

The study controlled for other variables that are known to affect Alzheimer’s risk including sex, age, physical activity, smoking, alcohol consumption and education.)

APOE4 carriers who ate the most unprocessed meat were at significantly lower risk of dying over the study’s 15-year period and had lower cholesterol than carriers who ate less. Go figure. Noncarriers, however, didn’tenjoy similar benefits from eating more red meat.

The study’s findings are consistent with two large U.K. studies.

One found that each additional 50 grams of red meat (equivalent to half a hamburger patty) that an APOE4 carrier consumed each day was associated with a 36% reduced risk of dementia.

The other found that older women who carried the APOE4 variant and consumed at least one serving a day of unprocessed red meat had a cognitive advantage over carriers who ate less than half a serving, and that this advantage was of roughly equal magnitude to the cognitive disadvantage observed among APOE4 carriers in general.

In all three studies, eating more red meat appeared to negate the increased genetic risk of APOE4.

Perhaps one reason men with the variant are at lower Alzheimer’s risk than women is that men eat more red meat.

These findings might cause chagrin to women who rag their husbands about ordering the rib-eye instead of the heart-healthy salmon.

But remember, the cognitive benefits of eating more red meat appear isolated to APOE4 carriers.

Nutrition is complicated, and categorical recommendations—other than perhaps to avoid nutritionally devoid foods—would best be avoided by governments and health bodies.

Readers can order an at-home test from any number of companies to screen for the APOE4 variant.

The Swedish researchers hypothesize that APOE4 carriers may be evolutionarily adapted to carnivorous diets, since the variant is believed to have emerged between one million and six million years ago during a “hypercarnivorous” period in human history.

The other two APOE variants originated more recently, during eras when humans ate more plants.

APOE4 carriers may absorb more nutrients from meat than plants, the researchers surmise. Vitamin B12—low levels have been associated with cognitive decline—isn’t naturally present in plant-based foods but is abundant in red meat.

Foods high in phytates (such as grains and beans) can interfere with absorption of zinc and iron (also high in red meat), which naturally declines with age. So maybe don’t chuck your steak yet.

To Sleep Better, Change What—and When—You Eat

The right foods and strategic scheduling can improve your shut-eye