The Microbiome Impacts Sleep Quality, and Vice Versa

Scientists are increasingly looking at how our gut microbiome (with roughly 100 trillion little bugs found in our digestive tracts) is connected to good sleep. Each of us are carrying entire civilizations in our guts, tiny empires of bacteria, fungi and other microbes. They help us digest food, regulate the immune system and generate vitamins like B12, among many other things. Most people pay little attention to the swill of microscopic bugs inside us. In fact, most scientists have overlooked the microbiome until relatively recently, when better research came along, shining a light on the creatures we carry.
Elevated levels of butyrate, which is a byproduct of dairy products and non-digestible carbohydrates, have also been shown to enhance sleep. In 2019, researchers from Washington State University gave rats tributyrin, an ingredient in butter which breaks down into butyrate. Their results, published in Scientific Reports, suggested that certain stages of sleep increased by 50 to 70 percent.

A more direct way of microbes altering our sleep is via the vagus nerve, the superhighway of the parasympathetic nervous system, which plays an important role in modulating mood, digesting food and regulating immune responses. However, a beneficial gut bacteria called Lactobacillus brevis has demonstrated the ability to activate this nerve and increase appetites, at least in mice. Scientists predict this is done by stimulating serotonin receptors and they tested it by injecting mice with drugs that block these receptors. They found the increased appetite was blocked.