How Gut Health Affects Sleep Quality + How To Enhance Both

Sleep and gut health issues are a lot like the chicken and the egg: It's hard to tell which came first. While suboptimal sleep can certainly lead to digestive needs, the opposite can also be true. To learn more about the surprising way gut health affects sleep—and how to enhance both—mbg looked into the research and chatted with sleep experts and functional medicine doctors. Here's what we found.

From a superficial standpoint, it can seem like the gut is only in charge of eating, digesting, and absorbing nutrients—but as any functional medicine expert will tell you, this complex organ plays a much larger role in the body. The microbes that live in the gut have a direct line of communication with the brain (called the gut-brain axis1), and they produce neurotransmitters, which influence sleep, mood, and more. 

According to a study that researched the role of the gut microbiome in sleep health, our circadian rhythm, and mood, one of those neurotransmitters, called GABA (or gamma-aminobutyric acid), is secreted by two types of bacteria in the microbiome2: Lactobacillus and Bifidobacterium.

"GABA enables the body and mind to relax, fall asleep, and sleep soundly throughout the night," clinical psychologist and board-certified sleep specialist Michael J. Breus, Ph.D., previously told mbg. According to the study, inadequate expression of GABA has been linked to suboptimal sleep and mood3.

Another neurotransmitter that is secreted by the gut and plays a role in sleep is melatonin. In fact, "the gut contains at least 400 times more melatonin4 than the pineal gland," says a study published in the World Journal of Gastroenterology. Melatonin tells your brain that it's time to go to sleep—which is an essential step in the bedtime process. 

Because these neurotransmitters—which directly affect sleep—are secreted in the gut, maintaining a healthy gut microbiome might enhance sleep quality.* Here are a few expert-backed ways to support gut health:*

On top of supporting overall gut health, one study of healthy individuals found that those who took probiotic supplements for six weeks experienced enhanced sleep quality over time5, compared to those taking a placebo.*

Another way to support a healthy gut is to eat plenty of diverse fiber-rich foods. As gastroenterologist Will Bulsiewicz, M.D., MSCI, once explained: The microbes that live in our gut are picky eaters. "They only like the fiber from specific foods," he said. 

In order to feed them optimally, it's important to make sure we're getting a good mix of soluble and insoluble fibers from a wide range of fruits, veggies, legumes, and whole grains. Here: four foods a GI doctor swears by for fueling your microbes.

As mentioned before, an unhealthy gut can contribute to suboptimal sleep, but poor sleep can also play a role in gut imbalance and the integrity of our intestinal lining. "Sleepless nights throw off your gut rhythm by adversely affecting the balance of favorable and unfavorable bacteria6 and compromising the gut wall," board-certified internist Vincent Pedre, M.D., writes for mbg. 

By establishing a calming nightly routine (think putting away your phone, taking a soothing bath, or listening to music before bed), you may enhance your sleep hygiene and gut health along with it.