Your Gut Health Could Affect How Well You Sleep, According to New Research

Your Gut Health Could Affect How Well You Sleep, According to New Research

Oct 22, 2021Karla Walsh

A new study reveals the fascinating link between gut microbes and your sleep quality.

If you're struggling to sleep as well as you once did, it could be the TV, sure. It could also be the stress and anxiety of the world we live in. Or it could be your microbiome , hints new research out of Japan.

Before we go any further, it's important to note that the study, which was published in the journal Scientific Reports, was performed on mice. Still, it might have some parallels in humans and direct the course of future research.
Details of the study

The study led by Professor Masashi Yanagisawa at the University of Tsukuba in Japan involved two groups of mice: One half ate their standard diet and took no medications, while the other half took a "powerful cocktail of antibiotics" for four weeks. Yanagisawa and his team then compared the gut bacteria of the two populations and found that they had a vast difference in quantity of metabolites, which are what food is broken down into as part of digestion. In particular, the mice who had taken antibiotics had very different neurotransmitter levels than normal—and as a result, they had much more tryptophan than controls, but almost zero serotonin.

The result of the study

Lacking important gut microbes like prebiotics and probiotics, the mice couldn't make any serotonin from the tryptophan they were eating. The antibiotic-treated mice were also lacking enough vitamin B6 metabolites, which boost production of the neurotransmitters serotonin and dopamine.

Here's where the sleep link comes in: After analyzing each mouse's sleep and brain activity via EEG, the microbiota-depleted mice had more REM and non-REM sleep at night. Unlike humans, mice are supposed to be up and at 'em at night and sleep during the day, so they actually were doing the reverse of their normal pattern. (So if this research translates to humans, we'd expect people with poor gut health to feel sleepy during the day but restless at night.) The microbiota-depleted mice also switched between sleep/wake stages more frequently than the controls—or, in other words, they had less sound, high-quality zzzs.

Yanagisawa believes that the missing serotonin may be causing the sleep abnormalities, but admits that more research is needed.

"We found that microbe depletion eliminated serotonin in the gut, and we know that serotonin levels in the brain can affect sleep/wake cycles," he said in the report. "Thus, changing which microbes are in the gut by altering diet has the potential to help those who have trouble sleeping."

Prioritize your own gut health

As the scientific community continues to build a more comprehensive gut health knowledge encyclopedia, it certainly can't hurt to prioritize your own gut health if you're noticing it's becoming more of a battle to snooze at night or feel drowsy during the day. (Especially if your other eating, drinking and lifestyle habits haven't changed much recently.) We do know that even without antibiotics, our modern lifestyle can affect our good gut bugs. And a healthy microbiome doesn't just impact our digestion and sleep; it's also been linked to lower risk for certain cancers, brain decline and chronic diseases like heart disease.

A great first place to start is to eat more plants, as they feed the good bugs in our gut much more than animal foods do. Fermented foods such as kimchi, yogurt and sauerkraut offer probiotics, while raspberries, garlic and beans supply prebiotics.

Best and Worst Food for your gut health

Best Food for your gut health


Probiotics are the "good bugs" and can be found in fermented foods like sauerkraut, kimchi, miso and yogurt. Eating probiotics adds good bacteria to your gut. The most common are Lactobacillus and Bifidobacterium. In addition to helping balance your gut bacteria, probiotics can help if you have diarrhea, boost your immunity and keep your heart and skin healthy (learn more about the health benefits of probiotics).

  1. Sauerkraut

Sauerkraut is made from cabbage and salt. During the fermentation process, microorganisms eat the sugar present in cabbage and produce carbon dioxide and acids. The probiotics created during fermentation assist with digestion and add good bugs to your gut.

One cup of raw cabbage has 36% of your Daily Value for vitamin C and 56% DV for vitamin K.

Enjoy sauerkraut on a hot dog, substitute it for pickles on a sandwich or burger, add it to potato salad, or put it on a cheese plate and serve your friends something good for their guts.

  1. Kimchi

Kimchi, also fermented cabbage, is the spicy Korean cousin to sauerkraut. It can have scallions, radishes and shrimp added to give it more flavor. Look for it in the refrigerated section near sauerkraut, other Asian sauces and pickles.

Kimchi is delicious added to a fried rice bowl with veggies and an egg.

  1. Kefir

Kefir is like drinkable yogurt. It's made when kefir grains, which are colonies of yeast and lactic acid bacteria, ferment the sugars in milk, giving it a slightly thicker consistency and tart flavor. Similar to yogurt, kefir is packed with probiotics.

Buy plain kefir (instead of flavored) to skip added sugars. Due to fermentation, kefir has a slightly tart and acidic taste, which makes it tasty added to a breakfast smoothie instead of milk. Or try substituting kefir for milk in overnight oats for a healthy combo of probiotics and fiber.

  1. Kombucha

Kombucha is a tart, fizzy tea made by adding a SCOBY (symbiotic colony of bacteria and yeast) and sugar to green or black tea. It's then fermented for a week or more. During fermentation alcohol and gases are produced, giving the kombucha natural carbonation. The amount of alcohol is usually less than 0.5% alcohol by volume (although some have been found to have closer to 2-3%).

Additionally, acetic acid and lactic acid bacteria are produced, the latter of which is known to function as a probiotic. When consuming kombucha made from green tea, you'll also get the antioxidant properties associated with tea. Keep in mind that some kombuchas, like those made from black tea, contain caffeine. Others have artificial sweeteners, which can negatively alter gut bacteria, so read labels.

  1. Miso

Miso is a fermented paste made from soybeans, barley or rice. Similar to other fermented foods, beneficial bacteria are produced in the fermentation process. You'll also get some protein if you eat miso made from soybeans. A little bit goes a long way, which is good since miso is also high in sodium.

Miso is great added to sauces, dressings and soup bases. Try it on this Miso-Maple Salmon.

  1. Tempeh

Tempeh is similar to tofu in that it's made from soybeans, but unlike tofu, tempeh is a fermented food, so it contains probiotics. Tempeh is made when soybeans are fermented and then pressed into a cake. It can then be grilled, sautéed or baked. Tempeh is high in protein, making it a good option for vegetarians and vegans. It's also packed with B vitamins, calcium, manganese, zinc and copper.

Try marinating then grilling tempeh, and add it to a salad. Or make tempeh tacos or Tempeh "Chicken" Salad.

  1. Yogurt

Yogurt is probably the most popular probiotic and for good reason. It's made when good bacteria are added to milk, where they metabolize lactose to form lactic acid and other beneficial bugs. Look for yogurt labeled with the "Live & Active Cultures" seal, which guarantees 100 million probiotic cultures per gram. A quick look at the ingredients list will also show you if there are bacteria in the yogurt. Don't eat dairy? The probiotics in yogurt help digest some of the lactose (milk sugar) so if you're lactose-intolerant, you may be able to enjoy yogurt. Plus, many companies now make dairy-free and vegan yogurts that contain probiotics.


Once you've got good bugs in your gut, you need to feed them so they can flourish to keep making more good bacteria. "Prebiotics are fibers that feed the beneficial probiotics in your gut," says Dianne Rishikof, M.S., RDN, LDN, IFNCP, a registered dietitian and integrative & functional medicine nutritionist at Health Takes Guts. "Ingredients to look for include galactooligosaccharides, fructooligosaccharides, oligofructose, chicory fiber and inulin." Fructans and cellulose are two other prebiotic fibers.

But don't get bogged down in the scientific names. In fact, you won't see most of these compounds listed on a label because they are present in foods that don't have labels—that is, fruits and vegetables (see our top picks for prebiotic-rich foods).

Focus on a variety of whole foods. "It's all about diversity, getting as much variety of plant-based foods as possible and hitting our recommended fiber intake of 30 grams per day," says Megan Rossi, Ph.D., B.H.Sc., RD, APD, The Gut Health Doctor. Apricots, dried mango, artichokes, leeks, almonds, pistachios and legumes, as well as polyphenol-rich foods, such as blueberries, strawberries, prunes, apples, flaxseed, olives and extra-virgin olive oil, are extra-high in prebiotics, she writes in her book, Eat Yourself Healthy.

  1. Jerusalem Artichokes

Also known as sunchokes, Jerusalem artichokes have 47 grams of fructans in 1 cup (regular artichokes clock in with just 6 grams per 'choke). One cup also delivers 3 grams of protein, 2.4 grams of fiber, 25% DV for thiamin, and 28% DV for iron. The majority of carbohydrates in 'chokes are inulin, a prebiotic fiber that provides food for your critters. Thiamin (a B vitamin) supports healthy hair, skin and nails, and iron helps form red blood cells.

Try sunchokes roasted with olive oil and garlic, raw in salads (they have a texture similar to water chestnuts) or in our Jerusalem Artichoke-Potato Soup with Crispy Croutons.

  1. Leeks

One leek has 10 grams of good-for-the-gut fructans, and 1 cup has 35% DV for vitamin K and 12% DV for vitamin C. Vitamin K helps your blood clot, and vitamin C is an antioxidant.

Leeks can be added to almost any dish—try adding them to an omelet or sautéing them to mix with roasted potatoes. Alternatively, rub whole leeks with oil and grill briefly; then toss with your favorite vinaigrette. Try our Oven-Braised Leeks that require only 15 minutes of prep.

  1. Onions

Onions are chock-full of inulin, fructans and fructooligosaccharides. Not only are FOSs a prebiotic that help build up gut flora, they also help lower cholesterol and relieve constipation.

Onions are highly versatile: add to soup or salad, grill and put on top of a turkey burger, or roast with herbs and serve as a side.

  1. Raspberries

One cup of raspberries has a whopping 8 grams of fiber, about one third of your Daily Value. Raspberries are a rich source of polyphenols, potent antioxidants that your gut microbes love to nosh.

Raspberries are delicious eaten fresh but are just as nutritious purchased frozen and thrown into a smoothie. Or add them to yogurt, oatmeal or a high-fiber cereal.

  1. Beans and legumes

Don't steer clear of beans for fear of having gas. It's actually a good sign. When beans and legumes, such as black beans, chickpeas, peas, lentils and white beans, reach the large intestine (colon), they are still intact. It's there that gut bacteria feed on them. This process is called fermentation. And the byproduct? Gas. So while it may be awkward, you can feel good about it because your bugs are hard at work.

Canned beans are a favorite—pick three types, rinse and mix for a simple bean salad. Or throw black beans on top of tacos. Lentils are delicious in soup.

  1. Asparagus

Not only is asparagus a powerful prebiotic for the gut, it may also be protective against certain cancers. This is because it contains glutathione, an antioxidant that fights off free radicals and other inflammatory compounds in the body.

Roasted asparagus can be made in just 15 minutes—simply toss the spears with olive oil, salt and pepper and oven-roast at 400°F for 10 to 15 minutes. Or shave raw asparagus over a green salad. Asparagus is also delicious added to pasta or an omelet.

  1. Garlic

Think food-as-medicine when you cook with garlic. Garlic may help reduce the risk of heart disease and is also anti-inflammatory in the body. Inulin and fructooligosaccharides are the two main fibers in garlic—a dynamic prebiotic duo.

Don't be afraid of buying whole garlic. Simply buy a garlic press and you can put the whole clove in there without having to peel it (yes, please). Garlic can be used to season almost any dish. Sauté it with onions and mix into a stir-fry or pasta.

  1. Bananas

Green bananas (the unripe ones) are best for the gut because they contain resistant starch, a type of indigestible fiber that produces more good bugs when your microbes feed on it. Resistant starch can also be created by cooking grains and then cooling them. So go ahead and make barley in bulk for the week. Ripe bananas are full of fiber too.

Eat bananas with peanut or almond butter for fiber, protein and healthy fat. Or add to overnight oats, Greek yogurt or a high-fiber cereal, or top whole-wheat toast.

  1. Pears

Pears are a prebiotic food for the gut but also contain pectin, a compound that helps lower cholesterol. One medium pear is just 100 calories but has 5.5 grams of fiber.

Add a dash of cinnamon to fresh pear slices for a tasty snack, bake a pear crisp, or mix diced pear into oatmeal for additional health benefits. The fiber in oatmeal, known as beta-glucan, helps lower cholesterol.

  1. Watermelon

Watermelon is naturally high in prebiotics with 1 gram of fructan per cup. One cup also has 14% DV for vitamin C, an antioxidant that fights inflammation, is the building block of collagen and increases the absorption of iron.

Watermelon is a summer staple that is tasty eaten plain. Find that boring? Make a refreshing beverage with it like we do in our Watermelon Cucumber Basil Seltzer or combine with feta and mint for a summery salad.


"Polyphenols are a type of plant chemical that gut microbes love," says Rossi. They are found in berries, apples, artichokes, red onions, tea, dark chocolate and other fruits and vegetables. Gut bacteria feed on polyphenols and produce beneficial substances.

Worst Foods for Gut Health

  1. Artificial sweeteners

Artificial sweeteners, such as aspartame, saccharin and sucralose, have zero calories and no sugar. They pass through the body without being digested, yet they come into contact with the microflora in the gut, negatively changing the composition, according to research. Even more, studies show that this altered microbiome can lead to conditions like glucose intolerance. More studies are needed (and will likely emerge in the near future) showing the connection between artificial sweeteners, gut bacteria and chronic diseases.

For now, keep an eye out for aspartame, saccharin and sucralose on the label of processed foods and drinks like diet sodas and other and zero-calorie beverages as well as some yogurts, granola bars and protein bars. These foods and drinks usually come with added sugar and salt anyway, so it's not the worst idea to limit them. Try kombucha in place of soda for a bubbly beverage with good-for-the-gut probiotics.

  1. Red meat

Carnitine, a compound found in red meat, interacts with gut bacteria to produce trimethylamine-N-oxide (TMAO), according to a study from the Cleveland Clinic. TMAO is associated with atherosclerosis—buildup of plaque in the arteries. This goes to show that the link between red meat and heart disease is not just about the saturated fat and sodium: how gut bacteria interact with red meat may play a role.

Eat red meat in moderation, and choose fatty fish, white fish, chicken or plant-based proteins like tofu and tempeh on the regular.

  1. Processed and Refined Foods

"While I wouldn't go as far as to say you need to cut certain foods out of your diet forever—food is about enjoyment too, after all—limiting highly processed foods loaded with additives and salt will do you and your gut microbes good," says Rossi. It's hard to study "processed foods" as a whole because each food has different ingredients, but the biggest issue with processed and refined foods is that they lack diversity and fiber and are often filled with added sugars, salt, artificial sweeteners and/or additives and preservatives. Your microbiome thrives on diverse fibers and polyphenols from a variety of colorful fruits, vegetables and whole grains.

  1. Alcohol

Research studies have found that alcoholism changes the intestinal microbiome. However, research is lacking on the effect of moderate alcohol consumption on gut bacteria and how the polyphenols in red wine interact with the gut. If you enjoy drinking, be sure to do so in moderation, which is one drink per day for women and two for men.

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