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 axis), and they produce neurotransmitters which influence sleep, mood, and more.
According to a study that researched the role of the gut microbiome on 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 microbiome: 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 mood.
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 melatonin 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.