A team of researchers at Nanjing Medical University in China has uncovered one of the key causes of insomnia. Most of us would likely never think to look for it where it’s hidden: in the gut microbiome. The team’s findings suggest gut microbes are often a contributing factor to insomnia.
Previous studies had already suggested a link between sleep and gut health. However, this new analysis confirms that the relationship is both causal and reciprocal. In other words, not only can microbes interfere with our sleep, but our sleep habits also affect the state of our gut.
The team proposed that in the future, insomnia could potentially be treated through the gut using probiotics and prebiotics. But, as lead author Dr. Shi Shanyun noted in an interview with Science Focus, further research is needed before doctors can prescribe gut-health strategies to help patients sleep better.
What Did the Study Reveal?
The team analyzed data from 387,000 individuals suffering from insomnia, as well as gut microbiome data from 26,500 people.
To explore the connection between insomnia and the gut microbiome, the researchers employed a statistical method known as Mendelian randomization analysis. This approach uses genetic information to understand causes and effects.
The scientists identified a number of microbes associated with insomnia. They also determined the composition of gut microbes in individuals with these genes and then checked whether participants with specific gut microbes were more likely to experience insomnia.
The analysis revealed that bacteria from 41 species could contribute to insomnia, at least in part.
However, Dr. Shanyun noted that some microbes play a more significant role than others. Specifically, 14 groups of bacteria were linked to a higher likelihood of insomnia, while eight groups were associated with a lower likelihood. Conversely, the researchers found that insomnia was related to a 43–79 percent reduction in seven groups of bacteria, and that in 65 percent of cases bacteria from 12 groups were at least four times more abundant than the rest of the gut’s population.
One class of bacteria—Odoribacter—was particularly closely linked to the risk of insomnia. These bacteria are typically associated with improved gut health.
Thus, the researchers discovered a vicious cycle: gut microbes can cause insomnia, but poor sleep also contributes to changes in the gut microbiome.
The study’s results were published in the journal General Psychiatry.
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