Not just your gut, prebiotics may improve quality of sleep as well

HOUSTON: Specific fibres known as prebiotics can improve sleep and boost stress resilience by influencing gut bacteria and their biologically active molecules, according to a study in rats that may lead to new dietary recommendations for sleep disorders.

The researchers, including those from the University of Colorado at Boulder in the US, explained that prebiotics are dietary compounds which humans cannot digest but serve as nourishment for the trillions of bacteria residing within -- the microbiome.

"The biggest takeaway here is that this type of fibre is not just there to bulk up the stool and pass through the digestive system. It is feeding the bugs that live in our gut and creating a symbiotic relationship with us that has powerful effects on our brain and behaviour," said Robert Thompson, a co-author of the study from the University of Colorado at Boulder.


In the study, published in the journal Scientific Reports, the scientists fed adolescent male rats a diet of either standard chow, or chow infused with prebiotics, and tracked physiological measures in the rodents before and after they were stressed.

According to the researchers, the rats on the prebiotic diet spent more time in restorative non-rapid-eye-movement (NREM) sleep, and after stress, they spent more time in rapid-eye-movement (REM) sleep -- believed to be critical for recovery from stress.

The scientists said rats eating standard chow saw an unhealthy flattening of the body's natural temperature fluctuations, and a drop in healthy diversity of their gut microbiome after stress.

However, they noted that the rats fed prebiotics were shielded from these effects.

When the researchers analysed the rats' fecal samples, they found that the rodents on the prebiotic diet had a substantially different "metabolome" -- or make-up of metabolites.

The prebiotic-fed rats had higher levels of fatty acids, sugars, and steroids, which the scientists believe may also influence behaviour via gut-brain signalling pathways.

They said the rats' metabolome also looked different after stress.

Rats on the standard chow diet saw dramatic spikes potentially sleep-disrupting metabolites, they said, adding that those on the prebiotic diet saw no such increase.

"Our results reveal novel signals that come from gut microbes that may modulate stress physiology and sleep," said Monika Fleshner, study co-author from the University of Colorado at Boulder.

The scientists however cautioned that it's uncertain whether just loading up on foods rich in prebiotics can promote sleep.

"You'd probably have to eat a whole lot of lentils and cabbage to see any effect," Thompson said.