To say these are stressful days is a radical understatement. We’re all under near constant stress. Many people are finding it difficult to manage their worry, fear, and anxiety—and finding it especially tough to get a good night’s sleep. I’m communicating with my patients remotely these days, and I’m hearing from so many of them about waking at 3 a.m. with a mind full of worried thoughts, or being too stressed out to fall asleep at all.
Amid all this unprecedented stress, some new research on prebiotics caught my eye. I’m always interested in the link between sleep health and gut health. Especially right now, in light of the stress we’re all facing, this new research seems particularly worth talking about.
Scientists at the University of Colorado Boulder conducted a fascinating study that shows how prebiotics can lower stress and help sleep, through feeding beneficial bacteria that lives in the gut microbiome. This study isn’t the first evidence of the value of prebiotics to sleep, but it is an important new piece of research that supports the connection between prebiotics, a flourishing, healthy microbiome, and healthy sleep.
What is a prebiotic?
Before we dig into this latest research, let’s get quickly acquainted with prebiotics. You’ve likely heard of probiotics–even if you’re not exactly sure what they are. Let’s take care of that. Probiotics are microorganisms that are friendly to the microbiome, the community of trillions of microorganisms that live throughout the body, with the largest grouping in the intestines.
This vast, ever-changing collection of microorganisms that make up the gut microbiome house a nervous system (the gut is now often referred to as a “second brain”). The gut microbiome produces and regulates hormones, as well as influencing immune function, digestion, metabolism, mood and stress. The health of the gut microbiome has vast effects on whole body health, and our risk for chronic diseases from diabetes to heart disease to cancer. I’ll talk more about the microbiome in a minute—and for a refresher, you can read some of my previous writing on the microbiome, here and here.
We get probiotics when we eat and drink fermented foods, from yogurt to sauerkraut, kefir and kombucha. And there are also a slew of probiotic supplements available—here’s a quick primer on how to choose a probiotic. Probiotics are great for the health of the microbiome, helping to maintain a healthy composition of beneficial bacteria in the body.
Prebiotics are actually food for probiotics and the other beneficial microorganisms that live within the microbiome. Prebiotics are compounds within food, which cannot be digested by the body. Instead, they feed and spur the reproduction of the tiny, good-for-you organisms living in your gut.
Prebiotics are present in foods that are high in fiber and resistant starches (starches that aren’t broken down by digestion). Some of the most prebiotic-rich foods include.
- Whole grains, such as barley, rolled oats, whole wheat and wheat bran
- Chicory root (this you can get in granules, and add to your cooking, or to drinks—including your morning coffee)
Prebiotics are also found in supplement form. Here’s a guide to some of the most well reviewed prebiotics by consumers, along with some tips for selecting a prebiotic supplement.
Prebiotics increase deep sleep and help control stress
Stress is a well-known disruptor to sleep. And research into the microbiome has demonstrated that the conditions of the microbiome can affect both stress and sleep, via the close and constant interaction between the gut microbiome and the brain.
What does this gut-brain communication axis look like? Research from the past decade has shown that the microbiome and the brain interact through at least three different paths:
An immune system pathway, where both the brain and the gut microbiome influence activity of immune cells, and affect one another in turn.
An endocrine system pathway, where both the brain and gut regulate production and release of hormones and neurotransmitters, including cortisol, serotonin, melatonin, GABA, dopamine and many others.
A nervous system pathway, where the body’s vagus nerve acts as a direct line of communication between the brain and the gut microbiome. In addition, microorganisms from the gut can travel the vagus nerve into the central nervous system, where they can directly affect brain activity, including sleep patterns and stress responses.
In this latest research, scientists at the University of Colorado Boulder investigated how prebiotics influence the composition of the gut microbiome—by composition, I mean the makeup of different types of bacteria, fungi, and other microorganisms. They also wanted to assess how prebiotics could affect stress and sleep, through their influence over the microbiome.
Scientists conducted their study in young male rats, feeding 1 of 2 groups food with prebiotics, and the other group food without prebiotics. After 5 weeks, rats in both groups were exposed to stress. Scientists found the prebiotic food eaters suffered less of the negative effects of stress on the microbiome.
Scientists also found that the prebiotic rats spent more time in deep, slow wave sleep after being on the gut-microbe-friendly diet. After their exposure to stress, the rats who ate a prebiotic diet spent more time in REM sleep. REM is a critical sleep stage for mental restoration, and helpful in the processing of emotionally-charged thoughts and in the recovery from stress.
This latest scientific discovery builds on earlier research, some of which comes from the same group of researchers, who have been studying the effects of prebiotics on stress and sleep, via the microbiome, for several years. In 2017, they published a study that echoes much of what is in the latest round of research:
Prebiotics aid sleep in part by creating a buffer against the negative impact of stress, by keeping the microbiome diverse and flourishing with beneficial bacteria, during stressful episodes.
Prebiotics appear to increase amounts of slow-wave sleep—the deepest form of non-REM sleep—and to increase amounts of REM in the wake of exposure to stress.
The newest study uncovered more information about the specific ways that prebiotics appear to blunt the stress response and improve sleep. Specifically, they identified changes to certain forms of microbial life—known as metabolites—changes that appear to reduce the brain’s stress response and to increase slow-wave and REM sleep.
This is an important step forward in understanding the relationship of prebiotics to sleep, which may bring us closer to prebiotic therapies that target these specific microbial changes, in order to boost sleep and lower stress.
So, how can you take advantage of the benefits of prebiotics? Eat fiber rich foods, including plenty of fruits, vegetables and whole grains! Even in our current social isolation, with less access to those farmer’s market vegetables, you’ve probably got prebiotic foods in your pantry—I’m talking about things like canned artichokes, rolled oats, whole grain bread. When you are able to get to the market for the fresh stuff, take my list of prebiotics above with you. And don’t forget frozen and canned vegetables as useful supplements right now to perishable fresh produce.
Other news about sleep and the microbiome
I’ve written before about sleep’s complex, dynamic relationship with the body’s microbiome. New research is coming in all the time, showing the connection between sleep health and gut health—a connection that runs in both directions.
A study from late last year found that sleeping poorly was linked to less diversity in gut microbes—and the better your sleep, the more diverse your microbiome is likely to be.
Remember, in the latest research we’re looking at, more diversity in gut microbes helped to lessen stress and improve sleep. That is the two-way street between gut health and sleep health in action. In addition to poor sleep, reduced diversity of the microbiome is also linked to a range of health issues, including mood disorders anxiety and depression, immune system dysfunction and autoimmune disorders.
Severe sleep apnea has been linked to reduced diversity of microorganisms in the nasal microbiome, in recent research. That’s right, microbiome is not confined to our intestines, though that’s where the largest community of microorganisms are. A less diverse composition of the nasal microbiome can increase inflammation, which affects the severity of sleep apnea, including via inflammation of the airway. There’s other recent research showing that obstructive sleep apnea in kids is associated with changes to the oral microbiome.
Both the quality and the quantity of sleep can impact the health of the microbiome. A 2019 study found that an additional 60 minutes of waking after falling asleep (which is a measure of both sleep quantity and sleep quality) was linked with a 26% reduction in the diversity of gut microbes. That’s after controlling for other factors that can affect microbiotic composition, including your dietary intake of fiber and fat, physical activity, and body-mass index. The study also found greater levels of daytime sleepiness linked to lower microbiotic diversity, and less sleepiness linked to more diversity.
Brand new research in mice revealed a link between a specific microbe—called Odoribacter—and sleep abnormalities.This suggests we’re likely to learn more about specific microorganisms residing in the gut microbiome having distinct effects on sleep.
How do you maintain a healthy microbiome?
Consuming both probiotic and prebiotic foods and supplements play a big part in keeping the gut microbiome healthy, diverse and supportive of sleep. The prebiotic foods I’ve talked about above contain fibers and resistant starches that won’t be broken down by the digestive system, but instead will go on to feed the healthy microbiotic life in the gut. The same whole food, fiber-rich diet is also great for sleep.
Limiting sugar is good for the gut. Sugar consumption can wreck a good night’s sleep. It also increases the presence of gut microbes that are linked to elevated insulin in the body. (A less healthy gut microbiome raises risk for type 2 diabetes.) Both natural and artificial sugars have negative impacts on gut health, with research suggesting that artificial sweeteners are particularly harmful to the health of the microbiome.
We all need as much resilience against stress, and as much high-quality sleep, as we can get right now. Paying attention to prebiotics in your diet is one way to help with that.
Michael J. Breus, PhD, DABSM
The Sleep Doctor™