Medically reviewed by
Dacelin St Martin, MD
Triple board-certified in Sleep Medicine,
Internal Medicine, and Pediatrics.
What is Inflammatory Bowel Disease? | The Role of Melatonin in the Gut |
A New Study & Findings | The Bottom Line
Overview
The relationship between gut health and sleep has been understood for some time, with research continuously demonstrating a symbiotic relationship between good gut health and good sleep.
However, a recent study has shone a light on the negative consequences of melatonin, a hormone that helps regulate our circadian rhythm, on the digestive tract in people with inflammatory bowel disease (IBD).[1]
Melatonin is a hormone secreted by the pineal gland and the gut.[2] It’s been long used as a sleep aid to help counteract the offset in sleep caused by jet lag and to help individuals who struggle to get a good sleep.[3]
In addition to its beneficial sleep properties, melatonin also exerts antioxidant and anti-inflammatory effects in the gut, making it an effective alternative treatment to help manage intestinal inflammation caused by IBD.[4] So what’s changed? Let’s find out.
What is Inflammatory Bowel Disease?
Inflammatory bowel disease, or IBD, is a chronic inflammatory disease affecting the digestive tract, causing symptoms such as abdominal pain, diarrhea, and rectal bleeding.[4]
It’s most commonly diagnosed at a young age and often flares up in bouts of pain and discomfort throughout an affected individual’s life.[4] Two major types of IBD are Crohn’s disease and ulcerative colitis.[4]
The exact cause of IBD is not yet understood. However, one major hypothesis believes it to be a combination of dysregulated immune responses to gut microbes in individuals with various genetic risk factors.[4]
The Role of Melatonin in the Gut
One hormone that can affect the gut microbiome is melatonin. Earlier research suggests that melatonin exerts various essential actions in the digestive system, such as by enhancing gut motility, secreting specific molecules, and enhancing the gut’s immune system.[2]
1) Motility
Motility is defined as the digestion and movement of food through the body.
Through interaction with melatonin receptors, melatonin acts on smooth muscle cells in the digestive tract to induce contracting and relaxing effects, stimulating gut motility.[2]
Studies demonstrated that smaller doses of melatonin sped up intestinal transit in animals, which may explain how it can be used to help offset certain symptoms of IBD.[2]
2) Secretion
Melatonin is involved in transporting ions in the intestines through various enzyme pathways.[2]
Research has shown that when melatonin is taken externally, it helps reduce diarrhea in rats with colitis, though the exact mechanism of how this occurred is yet to be confirmed.[2]
3) Immune System
Melatonin can affect the immune system in several ways.[2] First, it has been shown that melatonin promotes the activity of white blood cells, which are responsible for fighting infection and inflammation.[2]
Melatonin also protects certain white blood cells, called CD4 T cells, from cell death. It does so by sending signals to the immune system, which causes the immune system to exert the response the body requires.[2]
A New Study & Findings
As we can see, melatonin can help the gut in many ways. However, despite its ability to reduce inflammatory infiltration in IBD, a new study suggests that melatonin use can now worsen gut inflammation, as demonstrated in a mouse model during remission and delayed recovery of IBD.[1]
The gut contains an abundance of bacteria. In people with IBD, the composition of the bacteria differs from those without IBD.5 It has been shown that the microbiome composition in people with IBD contains greater amounts of Proteobacteria and Actinobacteria phyla and less of the Firmicutes and Bacteriodetes species.[6]
The study demonstrated that mice with chemically induced colitis treated with melatonin had a reduction in Bacteriodetes and an increase in Actinobacteria phyla, as is found in patients with insomnia, depression, and other mental illnesses.[1,7]
Interestingly, the researchers then assessed the effects of melatonin on the gut of mice with IBD after depleting the gut microbiome with antibiotics.[1] This resulted in a quicker remission from IBD, reduced inflammation, reduced abundance of Actinobacteria, and increased concentrations of Bacteriodetes, which may further explain the role of the gut microbiome in inflammation.[1]
Notwithstanding, melatonin use over prolonged periods of time in IBD can deteriorate intestinal inflammation and prolong recovery from colitis.[1] This effect could be linked to the increasing levels of white blood cells and inflammatory markers in the colon, which can lead to more inflammation and damage in people with IBD, despite melatonin’s effect on reducing the amount of IL-17 – an inflammatory marker that plays a role in regulating gut health.[1]
This study demonstrates the need for further human research to truly determine melatonin’s exact effects on the human digestive tract. However, this study may also provide an explanation for patients with IBD for whom melatonin has caused more harm than good.
The Bottom Line
The effects of melatonin on both brain and gut health is emerging, holding promise for future research. The many benefits of melatonin on sleep have been identified, yet there may be some contradictions regarding when melatonin can be safely used.
If you suffer from IBD and struggle to get a good night’s rest, you must discuss with your doctor or sleep specialist whether melatonin is right for you.
References:
- Da Silva, J. L., Barbosa, L. V., Pinzan, C. F., Nardini, V., Brigo, I. S., Sebastião, C. A., Elias-Oliveira, J., Brazão, V., Júnior, J. C. D. P., Carlos, D., & De Barros Cardoso, C. R. (2023). The Microbiota-Dependent Worsening Effects of Melatonin on Gut Inflammation. Microorganisms, 11(2), 460. https://doi.org/10.3390/microorganisms11020460
- Chen, C., Fichna, J., Bashashati, M., Li, Y., & Storr, M. (2011). Distribution, function and physiological role of melatonin in the lower gut. World Journal of Gastroenterology, 17(34), 3888. https://doi.org/10.3748/wjg.v17.i34.3888
- Herxheimer, A., & Petrie, K. J. (2002). Melatonin for the prevention and treatment of jet lag. The Cochrane Library, 2010(1). https://doi.org/10.1002/14651858.cd001520
- Vaghari-Tabari, M., Moein, S., Alipourian, A., Qujeq, D., Malakoti, F., Alemi, F., Yousefi, B., & Khazaie, S. (2022). Melatonin and inflammatory bowel disease: From basic mechanisms to clinical application. Biochimie, 209, 20–36. https://doi.org/10.1016/j.biochi.2022.12.007
- Zheng, L., & Wen, X. (2021). Gut microbiota and inflammatory bowel disease: The current status and perspectives. World Journal of Clinical Cases, 9(2), 321–333. https://doi.org/10.12998/wjcc.v9.i2.321
- Vrakas, S., Mountzouris, K. C., Michalopoulos, G. K., Karamanolis, G., Papatheodoridis, G. V., Tzathas, C., & Gazouli, M. (2017). Intestinal Bacteria Composition and Translocation of Bacteria in Inflammatory Bowel Disease. PLOS ONE, 12(1), e0170034. https://doi.org/10.1371/journal.pone.0170034
- Li, Y., Hao, Y., Fan, F., & Zhang, B. (2018). The Role of Microbiome in Insomnia, Circadian Disturbance and Depression. Frontiers in Psychiatry, 9. https://doi.org/10.3389/fpsyt.2018.00669
