The Close Connection Between Your Gut Health and Sleep Quality

The Close Connection Between Your Gut Health and Sleep Quality

The Close Connection Between Your Gut Health and Sleep Quality

Your gastrointestinal tract – your gut – has a direct link to your brain. Its health can affect your sleep, emotions, behavior, and physical capabilities, which is why it’s often referred to as “the second brain of the human body.” It goes the other way too; your brain health, including sleep habits, directly influences your gut health. You can think of your gut as a long tube that runs from the mouth to the anus. It has almost two tennis courts’ worth of surface area. Because it is exposed to the outside environment at both ends, your gut is home to a complex and dynamic population of trillions of bacteria, viruses, and fungi, which is known as the gut’s microbiota.

healthy and balanced gut microbiota is comprised of both good and bad bacterial species that have a bi-directional effect on health. The goal is to maintain a more “good” than “bad” bacterial balance. Humans all share about one-third of the gut microbiota’s composition, while about two-thirds of it is specific to each individual. Your gut composition evolves continuously throughout your life; your gut is sterile when you are born, but it immediately starts colonizing microbes.

The environment you live in and your diet have a profound effect on the composition of your gut microbiota. If you are a vegan living in New York City, you won’t have the same microbiota composition as someone who lives in Los Angeles and loves red meat. In addition to your daily environment, numerous lifestyle stressors can disrupt the normal balance of the gut microbiota. Processed foods, excess sugars, lack of fiber, inadequate hydration, exercise, emotional or mental stress, excessive use of antibiotics, and many other factors can influence your microbiota.

Some stressors can lead to an increase in pathogenic bacteria (“bad bacteria”) in your gut and can eventually result in adverse health conditions, such as inflammatory bowel disease, leaky gut syndrome, diabetes, obesity, and sleep disorders. Similarly, some stressors can positively impact the ratio. We all need a well-balanced gut microbiota for daily physical functioning – including metabolism, digestion, and immune function. In addition, we are beginning to understand the gut microbiota has significance for achieving optimal sleep.1,2

The gut and sleep

Research has revealed that those adults who report poor sleep quality also have a less than ideal gut microbiota, as well as less cognitive flexibility.3 However, the gut and sleep relationship is a two-way street – sleep disorders and disruptions are also known to negatively impact the gut microbiota.    

The relationship between the gut and sleep is complex. Does poor sleep cause an imbalanced gut microbiota, or does an imbalanced gut microbiota disrupt sleep? We know that not enough, inconsistent, or low-quality sleep are all linked to an increased risk for chronic health conditions such as diabetes, heart disease, obesity, and depression. In turn, these health conditions are linked to an imbalance of microbes in the gut known as dysbiosis. Beyond gut health, being tired increases your daily risk for mistakes, injury, or accidents – from errors at work to traffic accidents. Are you getting enough vitamin ZzZzZ? According to a recent State of Sleep survey from Gallup, 33 percent of U.S. adults report their sleep quality as fair or poor.4

What’s going on?

The brain has millions of neurons that connect it and its signals to the body – including the enteric nervous system (the “second brain”), which is a part of the nervous system that controls the GI tract. The vagus nerve connects a network of nerves in the gut to different regions of the brain. In fact, there is 24/7 communication between the GI tract and brain through the vagus nerve – referred to as the gut-brain axis. How exactly? There are many things about the gut-brain axis that researchers can’t yet explain, although we do know that bacteria in the gut can produce specific neurotransmitters, such as GABA, dopamine, and serotonin. Interestingly, research reports that 90 percent of serotonin is located in the gut.5 It is these neurotransmitters that can stimulate the neurons of the enteric nervous system to communicate back to the brain.

OK, but how is this connected to sleep?

Glad you asked. Melatonin, a sleep hormone primarily produced by the pineal gland – a pinecone-shaped gland located deep in the center of your brain – is responsible for managing the body’s circadian rhythm. But if the pineal gland is not functioning optimally, then the body relies on the gut as its back-up plan. In the gut, tryptophan can be converted to melatonin to help regulate the sleep-wake cycle.Tryptophan goes through several chemical reactions in this process, but it eventually converts to serotonin, and subsequently into melatonin.

However, this “back-up plan” requires the gut to function properly – so the supposition is that the status of your gut plays a role in how well you sleep. You can support your gut health to help you sleep by following these tips:


1. Get more out of your foods.

You are what you eat and don’t excrete. Consume more high-quality and nutrient-dense foods, drinks, and supplements, in appropriate portions for you. Take a digestive enzyme supplement, like Thorne’s Advanced Digestive Enzymes to support the digestion of carbohydrates, fats, and proteins.*

2. Don’t sweat the small stuff.

True, easier said than done, but less stress will impact your gut health – for the better. Know what stress does to you and the ways you can reduce it.7

3. Consume probiotic supplements or fermented foods.

Consistent, daily consumption of a good probiotic supplement or fermented foods like yogurt, kefir, or pickled vegetables support a balanced gut flora composition, promote brain health, and support digestion.*

4. Exercise every day.

Studies have consistently found that regular exercise will positively change the quality and quantity of the gut microbiota’s composition, providing you with many health benefits. Endurance exercise can help you gain a more stable and enriched microbiota diversity and improve the communication along the entire gut-brain axis.

5. Swap out sugars.

Research has also consistently shown that excessive sugar consumption increases the growth rate of the bad bacteria and disturbs the microbiota balance.9 Skip foods with added sugars; instead seek sources of carbohydrates with high fiber contents. Aim to eat 25-30 grams of fiber every day.

6. Avoid excessive use of antibiotics.

Antibiotics are among the most commonly prescribed drugs in the United States. They work by either stopping or destroying bacteria in the body – but they do it to both the good and the bad bacteria.

Do take an antibiotic when prescribed by a physician, but also consider taking a Thorne probiotic supplement – such as Sacro-B or FloraSport 20B® – to help maintain or reestablish a healthy gut microbiota.*


  1. Ramakrishna B. Role of the gut microbiota in human nutrition and metabolism. J Gastroenterol Hepatol 2013;28 Suppl 4:9-17.
  2. Tillisch K, Mayer E, Gupta A, et al. Brain structure and response to emotional stimuli as related to gut microbial profiles in healthy women. Psychosom Med 2017;79(8):905-913.
  3. Anderson J, Carroll I, Azcarate-Peril M, et al. A preliminary examination of gut microbiota, sleep, and cognitive flexibility in healthy older adults. Sleep Med 2017;38:104-107.
  4. The state of sleep in america 2022 report. Gallup.com. https://www.gallup.com/analytics/390536/sleep-in-america-2022.aspx. [Accessed April 3, 2023.]
  5. Terry N, Margolis KG. Serotonergic mechanisms regulating the GI tract: experimental evidence and therapeutic relevance. Handb Exp Pharmacol 2017;239:319-342.
  6. Zagajewski J, Drozdowicz D, Brzozowska I, et al. Conversion of L-tryptophan to melatonin in the gastrointestinal tract: the new high performance liquid chromatography method enabling simultaneous determination of six metabolites of L-tryptophan by native fluorescence and UV-VIS detection. J Physiol Pharmacol 2012;63(6):613-621.
  7. Mayer E. The neurobiology of stress and gastrointestinal disease. Gut 2000;47(6):861-869.
  8. Monda V, Villano I, Messina A, et al. Exercise modifies the gut microbiota with positive health effects. Oxid Med Cell Longev 2017;2017:3831972.
  9. Brown K, DeCoffe D, Molcan E, Gibson D. Diet-induced dysbiosis of the intestinal microbiota and the effects on immunity and disease. Nutrients 2012;4(8):1095-1119.