How many of us can really say we're getting quality of sleep these days? I'll admit, I'm working on it and the small changes I've made are paying off. Not only does the health of your gut play a role in your sleep, but sleep (or lack thereof) can also influence your gut. Curious? Let’s dive deep into the fascinating world of sleep and the microbiome.
What if I told you that you’re really only 10% human and 90% microbes? It’s true! Only 10% of your body is controlled by your cells and DNA, and the other 90% of your functioning comes from the trillions of microbes living in you and on you. In fact, you have 150 times more microbial DNA in your system than human DNA.
This microbial ecosystem is what scientists call the “microbiome,” and it includes viruses, bacteria, protozoa, and all kinds of living organisms. The microbiome encompasses all of the microorganisms and their genetic elements that are in and on their host—which is us! We are made up of thousands of little ecologies that have to work together to perpetuate the health of the whole.
The Human Microbiome Project was launched in 2008 to study the microbiome and its role in human health and disease. This has led to an explosion of scientific research, including more than 50,000 research papers in the last 5 years alone. It’s the biggest scientific revolution—ever—yet we are still just scratching the surface of all there is to know. For example, not long ago, scientists thought that certain areas of the body like the womb and blood were sterile. Now, they’ve discovered that we have 1,000 bacterial cells per milliliter of blood, and we also have them in our brain, cerebrospinal fluid, eyes, and everywhere else too. But by far, the gut has the highest concentration of microbes in the entire body.
Why is the gut called the second brain?
Growing up, you were probably taught that the brain is the master command center of the body. While that’s partly true, you have another command center that’s equally important, and it’s in your gut. Microbes have genetic elements that regulate all sorts of functions, including hormone production, metabolic activity, appetite, mood, and - sleep.
In some ways, you could say that the brain and gut are close friends because they work as intricate partners to run this complex system day in and day out. One of the ways they do this is by communicating back and forth through something called the “gut-brain axis.” The gut and the brain are directly connected through the vagus nerve which runs from your brainstem to your intestines.
The vagus nerve connects to the enteric nervous system, which encompasses all the nerves in your digestive tract. This system is the second most dense area of neuronal activity next to the brain. That’s why there’s a lot more truth to the phrase “gut feeling” than you may think.
All of the microbes in the gut have access to that enteric nervous system via the vagus nerve. This nerve also gives them direct access to the brain and vice versa—the brain can influence the gut microbes too. All day long, they talk to each other and relay messages back and forth.
If the bacteria in your gut are healthy, they can help to relay messages about when you’re full, when you need a little R&R, and when it’s time for bed. If they’re not healthy, they can make you crave sugar, feel anxious and depressed, or keep you counting sheep at night when you’re desperate for some rest.
Sleep affects the microbiome and the microbiome affects sleep. They have a cyclical relationship, and if one isn’t functioning properly, the other will be impacted too. Likewise, improving the health of the gut microbiome can have a direct impact on your sleep, and getting adequate rest can promote a healthy gut.
You may be familiar with the circadian rhythm’s role in regulating your sleep-wake cycles. Many other functions in your body run on an internal clock too, including the microbiome. The microbiome’s circadian rhythm is affected by what you eat, when you eat, and how you sleep. According to research, even just mild sleep deprivation can have a negative impact on gut health. A 2016 study looked at healthy young adults who had regular sleeping and eating patterns and looked at what happened to their microbiome after two nights of only 4.24 hours of sleep. The staggering results showed:
A decrease in insulin sensitivity
A decrease in healthy types of bacteria in the gut
Microbiome changes that are linked to type 2 diabetes
Growing evidence shows that sleep disorders, like circadian rhythm disorders, insomnia, and others, can upset the balance of healthy bacteria in the gut, and this damage is linked to a range of health problems, including metabolic syndrome, obesity, diabetes, and inflammatory disease. Lately, a lot of attention has been focused on the role of sleep in the development of Alzheimer’s disease later in life. Some new research suggests that the bacteria in the microbiome may be behind these cognitive changes. A 2017 study of healthy older adults found that better sleep quality was linked to better cognitive functioning and a healthier microbiome.
If you think about the digestive tract, it’s really one long tube that’s open on both ends. The only way that things can enter into the body is through the intestinal lining in the gut. The regulation of what is allowed to pass in through that lining is a highly important junction for chronic illness—you want healthy nutrients to enter in and toxic junk to stay out.