Sleep is a really complicated phenomenon. To break it down simply, a sleep cycle is comprised of periods of rapid eye movement (REM) and non-rapid eye movement (NREM). REM accounts for about 20% of active sleep time, whereas NREM covers the remaining 80% (1,2). Although it’s important that everyone gets quality sleep with enough REM and NREM sleep, people with IBD and IBS are especially missing out on this. For instance, reports show that up to 80% of people with Crohn’s disease don’t get a good night’s sleep (1,3), and IBD patients need this sleep to improve their health. Although people with gut issues could certainly use the extra rest, there’s so many mechanisms involved in sleep health that everyone can learn from! Here’s a list of some of the most important relationships between sleep and the body.
The Microbiome
Our sleep and microbiota composition both change throughout the day and as we age (4). This dynamism makes studying the relationship between sleep and gut microbiota challenging. For example, many studies to date focus on a single time point, which poorly represents all the changes our microbiome goes through throughout the day (4).
Unsurprisingly, people who deal with illness, especially chronic conditions, may have a lower quality of life. Those with IBD are no different; in fact, some estimates suggest that up to 1 million of the 1.4 million Americans with IBD experience sleep disturbances, which can affect disease activity (and vice versa) and quality of life, among countless other consequences (5) . It’s been suggested that bacterial dysbiosis (an imbalance of the gut microbiome) characteristic of IBD may also contribute to poor sleep health, but melatonin, often referred to as the sleep hormone, could help people with IBD and IBS by helping the microbiome get more in balance and prevent the emergence of dangerous bacteria in the gut. A study suggested that melatonin helps regulate gut microbiota in those with colitis, a type of IBD, but more research is needed to determine how this actually works (6).
IBS unfortunately has several additional links to poor sleep as well. Sleep disturbances, altered sleep patterns such as abnormal REM sleep, and an imbalanced gut microbiome are all characteristic features of IBS (4,7,8). Restoring balance and diversity in the microbiome, such as through fecal microbiota transplantation (FMT), has helped restore proper sleep in people with IBS (9). For instance, patients who had both a functional gastrointestinal disorder (such as IBS) and a psychiatric disorder had better sleep and relief from anxiety and depression symptoms following FMT, suggesting that improving diversity of the microorganisms that make up one’s gut microbiota can help with mood (9).
Circadian Rhythm
This visual illustrates all the different connections between the body, the brain, and sleep physiology (10).
The circadian rhythm is your body’s internal clock. It dictates sleep cycles and everything that comes with them, such as changes in your hormonal balance. The central clock is located in the brain and it is affected by several factors, including light exposure, diet, and gut microbiota. Microbiota can also affect activity in organs or cells that are involved in controlling circadian rhythms with the central clock (4). The organs and cells are referred to as peripheral clocks. Interestingly, 10% of commensal species (which get nutrients or other resources from other species) of gut microbiota in humans have demonstrated circadian fluctuations every day (11). This shows that the gut inherently has some sleep cycle properties.
When the balance and health of gut microbiota are disrupted, circadian rhythm can be affected and lead to intestinal inflammation (1). It’s also been shown that these disturbances make the gut lining more porous, allow unwanted things to get in and out of the gastrointestinal tract, causing an increase in inflammation and inappropriate immune activity (1). This is known as gut permeability, and it is related to many negative health consequences such as leaky gut syndrome.
If it wasn’t already clear why a consistent circadian rhythm is so critical for proper sleep and gut health, this evidence will certainly reinforce this fact.
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Research shows that disruptions to circadian rhythm are linked to a higher risk of an IBD flare-up, suggesting that poor sleep can be an indicator of disease activity (1,12).
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Patients with ulcerative colitis have shown that poor sleep is independently related to both depression and lower IBD-related quality of life (1).
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Crohn’s disease patients have been found to have lighter sleep and circadian misalignment linked to more aggressive disease activity (1).
Inflammation and Immunity
We’ve touched on inflammation and how it affects circadian rhythm, but its relationship with the immune system is also worth discussing. NREM sleep is just one of many critical factors that supports healthy immune responses. When NREM sleep is disrupted, so too is your body’s ability to effectively protect you from infection and inflammation (1,13). When you’re not in NREM sleep, you’re in phases of REM and wakefulness, both of which are instances when the body is less responsive to attacks (1,14,15).
With respect to IBD, inflammation can be even more of an issue. Researchers have found that among IBD patients with inactive disease, poor sleep was more likely to trigger a relapse in disease activity (1,16,17). This suggests that poor sleep can be an indicator of inflammation without the presence of other gastrointestinal symptoms (1). Active inflammation and bad sleep has reduced the quality of life of people with IBD, which is never something to overlook, especially with chronic, invisible illnesses like this (18). As if making sure people with IBD get enough shut-eye wasn’t emphasized enough, it’s pretty important to monitor their sleep patterns as a core aspect of short- and long-term health. And it’s not just physical health that can be impacted when IBD patients have disrupted sleep patterns; fatigue and lower psychological well-being are all interconnected (19).
Food Intake and Metabolites
We’ve established that food intake can affect the composition of gut microbiota and that this has an effect on circadian rhythm. The microbiota-gut-brain axis that interconnects all these processes is affected by numerous factors, such as antibiotic use and fiber intake. Microbial metabolites, which are the byproducts of metabolism that gut bacteria feed on, are critically involved in this. Foods that contain non-digestible fibers, such as oat bran and beans, promote higher levels of microbial metabolites, which can have anti-inflammatory properties and improve sleep physiology, all starting from the gut (4) Dietary polyphenols, which can be found in foods like berries, can prevent cognitive impairments experienced with sleep deprivation. Polyphenols work to protect against issues like memory loss or problems staying focused, but these benefits can be dampened when using antibiotics, which are known to impact balance and diversity of microorganisms in the gut microbiome and cause health issues. Polyphenols work in processes that utilize microbial metabolites to protect us against the effects of poor sleep (4).
One set of critical metabolites is short chain fatty acids (SCFAs). In the gut, these little molecules can do a lot for sleep health. Propionate and butyrate, two important SCFAs, have dynamic levels throughout the day to affect sleep and genes related to circadian rhythm. Disrupted sleep is known to affect the levels of SCFAs, and the relationship is thought to go both ways, where the metabolites affect sleep quality as well (20). An example that highlights this two-way relationship is how administration of butyrate increased NREM sleep, which, as discussed, is of benefit to the body (4).
Psychological Factors
Unsurprisingly, sleep and stress both influence each other, and this relationship is at least partially influenced by the microbiota-gut-brain axis (4). Stress is kind of a multi-purpose destructor of gut health, as it’s a factor that causes gut permeability, inflammation, immune responses, and imbalances in gut microbiota, which we know lead to disruptions in sleep (4). Cortisol, also known as the stress hormone, is released in varying levels depending on the type of stress. Too much cortisol, especially long-term, can have a negative impact on immune health and more. Since a more porous intestinal tract (which can occur with an overactive immune system) is linked to the development of Crohn’s disease, this relationship is definitely worth investigating (21). Furthermore, ergothioneine, a metabolite that helps to prevent stress-related sleep changes, represents yet another way that microbial metabolites are implicated in sleep health (22). Stress is just one psychological factor that affects sleep and people with IBD and IBS--mood disorders and other mental health issues are also involved.
Here’s a few key points on some research related to sleep and psychological wellness:
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Anxiety has been shown to be the strongest element related to sleep disturbances (4).
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Vedolizumab therapy for IBD patients helped them with their symptoms of anxiety and depression, and they had better sleep within six weeks and up to a year (23).
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Ulcerative colitis patients with depression who identify as female had worse sleep, with both these factors impacting sleep separately (24).
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Crohn’s disease patients who took benzodiazepines, which are commonly used to manage anxiety, justify their use of this medication as a sleep aid. This suggests that there is an overlap between mood disorders and poor sleep among people with Crohn’s disease (21).
The Vagus Nerve and Serotonin
Many people tend to refer to serotonin as the happy hormone, but it’s much more than that. While the specific roles of serotonin are not well understood, it’s thought to be a critical neurotransmitter involved in modulating and monitoring sleep. In studies on rodents, depleted levels of serotonin affected NREM sleep, and antibiotic-induced depletion of gut microbiota diversity led to lower intestinal serotonin levels (4). This provides a link between the gut microbiome, serotonin, and sleep health. Research even says that 95% of serotonin is made in the gut (25)! As for the vagus nerve, it’s been suggested that this important cranial nerve transports serotonin along the brain-gut axis to mediate these functions (26). This nerve has also been implicated in the relationship between sleep and gut microbiota (4).
Overall, there are countless links between sleep, gut health, and the microbiome. With so many factors involved, good sleep can be quite a challenge for people with altered gut microbiota, since it’s interconnected with various other modulators of sleep health. This is yet another reason to monitor your microbiome. With the Injoy microbiome test kit, you can learn about your levels of sleep-friendly bacteria, and receive recommendations on how to get more of the gut bacteria you want, and reduce the ones that could be preventing you from getting the sleep you need. Download Injoy today!
- https://link.springer.com/article/10.1007/s11894-020-0746-x
- https://www.ncbi.nlm.nih.gov/books/NBK19960/
- https://pubmed.ncbi.nlm.nih.gov/25732745/
- https://www.cell.com/trends/molecular-medicine/fulltext/S1471-4914(21)00185-4?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS1471491421001854%3Fshowall%3Dtrue
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3995194/
- https://www.nature.com/articles/s41598-020-59314-7
- http://dx.doi.org/10.1016/0016-5085(92)91089-M
- https://pubmed.ncbi.nlm.nih.gov/15667495/
- https://www.sciencedirect.com/science/article/abs/pii/S0165032718301939?via%3Dihub
- https://www.sciencedirect.com/science/article/abs/pii/S1087079220300836?via%3Dihub
- https://www.cell.com/cell/fulltext/S0092-8674(14)01236-7?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0092867414012367%3Fshowall%3Dtrue
- https://www.cell.com/cell/fulltext/S0092-8674(13)00462-5?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0092867413004625%3Fshowall%3Dtrue
- https://pubmed.ncbi.nlm.nih.gov/30388243/
- https://pubmed.ncbi.nlm.nih.gov/19209176/
- https://pubmed.ncbi.nlm.nih.gov/23099140/
- https://pubmed.ncbi.nlm.nih.gov/23945186/
- https://pubmed.ncbi.nlm.nih.gov/29507468/
- https://pubmed.ncbi.nlm.nih.gov/21830266/
- https://pubmed.ncbi.nlm.nih.gov/23602816/
- https://journals.physiology.org/doi/full/10.1152/physiolgenomics.00039.2020
- https://academic.oup.com/ibdjournal/article-pdf/26/8/1251/33505081/izz258.pdf
- https://pubmed.ncbi.nlm.nih.gov/32467627/
- https://pubmed.ncbi.nlm.nih.gov/30159665/
- https://pubmed.ncbi.nlm.nih.gov/27796768/
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5526216/
- https://www.psychologytoday.com/ca/blog/the-athletes-way/201910/the-vagus-nerve-may-carry-serotonin-along-the-gut-brain-axis
