A new study reveals the fascinating link between gut microbes and your sleep quality.

Advertisement

The unpredictability of 2020 has impacted many of our healthy habits. From stress eating to working from home (AKA working from a not exactly ergonomic couch) to staying up too late bingeing The Crown and Emily in Paris (that can't be just us, right?!), it's been a challenge to stay physically and mentally well—not to mention the actual virus that's drastically changed our daily lives.

If you're struggling to sleep as well as you once did, it could be the TV, sure. It could also be the stress and anxiety of the world we live in. Or it could be your microbiome, hints new research out of Japan.

Before we go any further, it's important to note that the study, which was published in the journal Scientific Reports, was performed on mice. Still, it might have some parallels in humans and direct the course of future research.

The study led by Professor Masashi Yanagisawa at the University of Tsukuba in Japan involved two groups of mice: One half ate their standard diet and took no medications, while the other half took a "powerful cocktail of antibiotics" for four weeks, according to a recap of the results from the university. Yanagisawa and his team then compared the gut bacteria of the two populations and found that they had a vast difference in quantity of metabolites, which are what food is broken down into as part of digestion. In particular, the mice who had taken antibiotics had very different neurotransmitter levels than normal—and as a result, they had much more tryptophan than controls, but almost zero serotonin.

Lacking important gut microbes like prebiotics and probiotics, the mice couldn't make any serotonin from the tryptophan they were eating. The antibiotic-treated mice were also lacking enough vitamin B6 metabolites, which boost production of the neurotransmitters serotonin and dopamine.

Here's where the sleep link comes in: After analyzing each mouse's sleep and brain activity via EEG, the microbiota-depleted mice had more REM and non-REM sleep at night. Unlike humans, mice are supposed to be up and at 'em at night and sleep during the day, so they actually were doing the reverse of their normal pattern. (So if this research translates to humans, we'd expect people with poor gut health to feel sleepy during the day but restless at night.) The microbiota-depleted mice also switched between sleep/wake stages more frequently than the controls—or, in other words, they had less sound, high-quality zzzs.

Yanagisawa believes that the missing serotonin may be causing the sleep abnormalities, but admits that more research is needed.

woman sleeping in bed with eye mask
Credit: getty images / laylabird

"We found that microbe depletion eliminated serotonin in the gut, and we know that serotonin levels in the brain can affect sleep/wake cycles," he said in the report. "Thus, changing which microbes are in the gut by altering diet has the potential to help those who have trouble sleeping."

As the scientific community continues to build a more comprehensive gut health knowledge encyclopedia, it certainly can't hurt to prioritize your own gut health if you're noticing it's becoming more of a battle to snooze at night or feel drowsy during the day. (Especially if your other eating, drinking and lifestyle habits haven't changed much recently.) We do know that even without antibiotics, our modern lifestyle can affect our good gut bugs. And a healthy microbiome doesn't just impact our digestion and sleep; it's also been linked to lower risk for certain cancers, brain decline and chronic diseases like heart disease.

A great first place to start is to eat more plants, as they feed the good bugs in our gut much more than animal foods do. Fermented foods such as kimchi, yogurt and sauerkraut offer probiotics, while raspberries, garlic and beans supply prebiotics. Learn more about the best and worst foods for your gut, and if you're feeling inspired, join our 30-day healthy gut challenge.