Certain bacteria and micro-organisms present in the digestive tract participate in the regulation of serotonin, which is essential for maintaining a good sleep/wake cycle.
-1606746109.jpg "The bacteria in our microbiota also regulate our sleep")
- The bacteria in our microbiota regulate the serotonin we produce.
- Without them, our body does not synthesize enough of them, which affects REM sleep, the most important phase.
- Serotonin is the hormone responsible for the circadian cycle, the one that tells us when to sleep and when to stay awake.
Sleep is a complex process. And this essential phase for the body is too often abused because of our rhythms of life. Yet it is during sleep that our body regenerates itself, that our memories are fixed, that our body updates itself to better face a new day. Researchers from the University of Tsukuba (Japan) have discovered that our sleep is also dependent on the bacteria and microorganisms present in our digestive tract, because they are the ones that regulate serotonin, essential for maintaining a good circadian cycle. The results of their research were published on November 11, 2020 in the journal Scientific Reports.
The interest of the microorganisms of our microbiota
To fully understand the situation, the researchers gave mice antibiotics for four weeks. While antibiotics are known to help our body defend itself, they can also eliminate certain bacteria present in our digestive tract, which weakens the microbiota.
The researchers compared the intestinal contents of these mice rid of these microorganisms with that of control mice having the same diet. During digestion, food breaks down and becomes metabolites, or small molecules. “We found over 200 metabolite differences between groups of mice. About 60 normal metabolites were missing in mice lacking microbiota, and the others differed in quantity, some more and some less than in control mice.”, says Masashi Yanagisawa, professor at the University of Tsukuba.
Once this observation was made, the researchers tried to understand the usefulness of these metabolites. By analyzing the enrichment of all the metabolites, they discovered that the biological pathways most affected by antibiotic treatment were those involved in the production of neurotransmitters. Thus, the tryptophan-serotonin pathway was almost blocked in mice lacking microbiota. This shows that without the right gut microorganisms, the mice could not produce serotonin from the tryptophan they ate. Likewise, these mice had a deficiency in vitamin B6 metabolites, which accelerate the production of serotonin and dopamine.
Serotonin, a sleep regulator
Finally, the mice were subjected to an electroencephalogram, in order to see their brain activity during their sleep. Compared to control mice, the paradoxical sleep of rodents without microbiota was more disturbed. The number of REM sleep episodes was higher during the day and at night, while the number of non-REM sleep episodes was higher during the day. In other words, the mice lacking microbiota alternated more frequently than the others between sleep and wakefulness phases.
“We found that depletion of microbes eliminates serotonin in the gut, and we know that serotonin levels in the brain can affect sleep/wake cyclesemphasizes Masashi Yanagisawa. So changing the microbes in the gut by altering the diet can help those who have trouble sleeping..”
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