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How What You Eat Affects Your Sleep

Experts say what and when you eat all day long definitely affect your slumber.
Image: Cup of coffee with milk
Your afternoon coffee may be keeping you up. Caffeine can stay in the bloodstream for up to six hours after you consume it. John Brecher

Whether or not we get high-quality slumber at night is dependent on a lot more than what time we turn in at night and what time we set the alarm for. That includes everything from how much exercise we get to how much time we spend in the sun to how much time we spend looking at our phones and computer screens. And the combination of foods and drinks we fuel our bodies with throughout the day also get an important spot on that list.

It might seem obvious why a double espresso after dinner might disrupt your sleep that night — as might a greasy, late-night cheeseburger with French fries. The connection between a noontime salad and your slumber is somewhat less straightforward — but it’s an important one, Ana Krieger, MD, MPH, Medical Director of the Center for Sleep Medicine at New York-Presbyterian and Weill Cornell Medicine, tells NBC News BETTER.

Eating an overall healthy and nutrient-rich diet affects our brain health and activity — and in turn, our sleep, she explains.

“Eating healthy and allowing the body to absorb proper nutrients provides the brain with the chemical environment that it needs to produce the neurotransmitters that it needs to maintain adequate sleep,” Krieger says. The nutrients we get from food serve as the building blocks for other minerals and proteins that are needed to create the amino acids that are involved in sleep, she says.

Although the research behind how various nutrients in our diet affect our sleep is young, the evidence thus far is intriguing.

Data shows that eating less fiber, more saturated fat and more sugar throughout the day is linked with lighter, less restorative sleep.

In one study, researchers tracked diet and sleep for a group of healthy adults over the course of five nights and found that indeed, food choices during the day did affect sleep. The researchers chose what the study participants ate for the first four days of the study, but not on the final day of the study. The data showed that eating less fiber, more saturated fat and more sugar throughout the day was linked with participants getting lighter, less restorative sleep, with more awakenings throughout the night.

When we eat is connected to sleep, too

There’s also a connection between sleep and how we metabolize food. Diet and food choices help regulate our circadian rhythm, the roughly 24-hour cycle that our body follows each day, Kristin Eckel-Mahan, PhD, Assistant Professor at the Center for Metabolic and Degenerative Diseases at The University of Texas Health Science Center of Houston, says. Our circadian rhythms keep our body clock running on time, which in turn keeps all of our bodily functions running on schedule — such as falling asleep at night, waking up in the morning, feeling hungry when we need energy and metabolizing the food we eat.

That means behaviors like shifting our eating patterns or altering what we eat drastically (like switching to a very high-fat diet) can actually reprogram the various clocks our body runs on, Mahan says, “putting them on a different time zone than the master circadian clock in the brain [which controls sleep].”

That’s why what and when we eat affects sleep — and conversely sleep health affects metabolic health, too.

Research shows poor sleep patterns have been linked to eating more overall, worse diet quality and higher rates of obesity and metabolic diseases. While psychological factors (like being tired and making worse food choices) contribute to those problems, metabolic processes — like increased levels of the hormones that tell our bodies we’re hungry getting released when you’re sleep deprived — also play a role.

It’s important for people to know that both what you eat, as well as the timing of when you eat, matter when it comes to sleep and long-term health outcomes, Mahan says. “Making good nutrient choices will optimize the circadian alignment between our clocks.”

Your best bet when it comes to eating right for good sleep? Focus on general healthy eating guidelines — and not skipping or shifting meals too much, Krieger says.

Here are a few other tips to keep in mind:

1. Pay attention to caffeine intake (and when you’re getting it)

Caffeine makes us feel more alert by blocking production of the chemicals in the brain that tell our bodies to sleep — and increasing adrenaline. The stimulant affects everyone’s bodies differently, explains Georgia Giannopoulos, a registered dietician at NewYork-Presbyterian. That’s why some people can handle two Cokes with dinner and fall right asleep, while others can’t handle more than one morning coffee.

It’s important to note that caffeine can stay in the bloodstream for up to six hours after you consume it, which is why nearly every sleep guideline you read suggests limiting caffeine in the afternoon and evening hours.

If you’re not having trouble sleeping, you don’t necessarily need to limit or cut back on caffeine, but if you are looking for a way to improve your sleep, how much and when you drink caffeine throughout the day should be one of the first things to consider, Giannopoulos says.

2. Lay off the booze before bedtime

Yes, a glass of red wine (or another cocktail) can definitely make you drowsy, but there’s research that shows it actually disturbs the quality of your sleep later in the night, Giannopoulos explains. Alcohol has the effect of knocking you out pretty hard right away, so your body spends more time early in the night in the deep sleep stage than it otherwise might. But your sleep cycle rebounds and your brain tends to then keep you in the lighter sleep stages (including rapid eye movement or REM sleep, when you dream) the rest of the night. The result: you wake up feeling less rested after a night of heavy drinking or drinking too much too close to when you try to sleep than on nights you skip the libations.

The good news is you don’t necessarily need to swear off a drink or two. Giannopoulos suggests drinking in moderation and not drinking too close to bedtime.

3. Avoid heavy spicy or fatty foods too close to slumber

Save the Buffalo wings and the nachos with hot sauce for daytime tailgates (in moderation!). Heavy foods that are spicy or fatty are tougher for the stomach to digest than lighter ones (like bananas or whole grains). And indigestion before bedtime makes it harder for your body to relax and drift off to slip.

And that’s also why experts recommend…

4. Breakfast like a king and supper like a pauper

Similarly, a large quantity of food eaten in a short period of time takes your body longer to digest and can be more taxing. Remember though that everyone’s body is different — so some people may have to be careful about eating too much before bed than others, Giannopoulos says. Again, if big dinners don’t disrupt your sleep there’s no need to necessarily change your habits. But if you are looking for things that might be affecting your sleep quality, timing of meals is an important one to keep in mind.

And particularly for people with acid reflux disease or other digestive problems, remember these effects may be exacerbated, she adds.

5. Snack wisely before bed

While you shouldn’t go to bed with a stuffed stomach, your stomach doesn’t need to be empty either. A growling stomach can definitely keep you awake, Giannopoulos says.

It’s tough to do definitive research to show that certain foods promote sleep over others, since there are so many factors that contribute to good or poor quality sleep, Krieger notes. But there are some foods for which it would make intuitive sense that they promote sleep — and some preliminary studies have been done that support the claims, she explains.

Bananas, for example, contain serotonin, turkey contains tryptophan and berries contain some melatonin — which are some of the building blocks for the chemicals our brains need to make for sleep. There is some research that suggests individuals with insomnia did fall asleep faster after drinking tart cherry juice, which is high in melatonin and inflammatory cytokines, all of which are known to play a role in the sleep process. (Though the researchers who conducted that study point out that such an effect was not as great as results for other more thoroughly vetted insomnia treatments.)

6. Cut back on sugar

Overall, limiting the sugar you eat — particularly added sugars — is well connected to better health. And watching the sweet stuff may help you sleep better, too, according to the National Sleep Foundation.

Too much sugar in your diet has a direct effect on blood sugar levels, which very directly influence your energy levels throughout the day. Sugar boosts energy levels quickly, but they crash quickly after that, too. Those energy surges and dips might lead you to reach for extra caffeine, sneak in poorly-timed naps or eat other foods you wouldn’t normally — all of which can affect sleep.

Limiting sugar helps keep energy consistent throughout the day, so you can maintain other healthy habits throughout the day — and catch quality Zs at night.

7. Stay hydrated all day long

If you’ve ever been dehydrated during a workout or even on a hot day, you know your body doesn’t function at its best when you don’t get enough water. You might get irritable, fatigued and have trouble concentrating. Likewise, being dehydrated can disrupt your sleep, too, Giannopoulos explains.

A lack of water dries out your mouth and nasal passages, which might increase snoring (which can pull you out of or prevent you from getting into deep, restorative sleep) and may cause hoarseness of breath in the a.m. You also may be more likely to get leg cramps, which can wake you up, too.

But that doesn’t mean chugging a bottle of water right before bed. (In fact, sleep specialists advise against this, at too many fluids right before bed may wake you up because you need to pee during the night.) Instead, stay well-hydrated all day long, which will help keep your fluid levels up throughout the night, too.

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