Nov. 4, 2021 -- Loads of people have trouble sleeping, and for a host of reasons: stress, too much caffeine, too much screen time before bed, and trouble shutting down at the end of the day are just a few. But perhaps the toughest sleep-related problem to handle is a body clock that’s off its rhythm.

Think swing shift workers, international travelers, or people dealing with a lack of natural light, the aging process, or poor sleep hygiene. Chronic disruption of internal clocks is tough on the body and can lead to various health problems. These range from sleepiness and lack of alertness to more serious issues, such as cardiovascular disease, diabetes, and obesity.

Treatments for disrupted circadian rhythms often include melatonin, light therapy, sleep therapy, and dietary changes, among others. While successful for some people, others have yet to find a fix and continue to have sleep troubles.

One of the latest attempts at helping those with disrupted circadian rhythms involves changes to the diet. Researchers from the University of Colorado, Northwestern University, and the University of California San Diego teamed up with the Office of Naval Research to see if prebiotic foods may be able to regulate rhythms.

“Humans have a complicated, integrated system, and stressors impact the mind and body globally,” says Monika Fleshner, a professor of integrative physiology at CU Boulder and lead researcher on the study. “We can’t control the impacts of our age, genetics, or gender on sleep patterns, but what can we control?”

That’s exactly what the team set off to find out.

The Study

To answer that question, at least in part, Fleshner and her team worked with the Navy because its sailors often travel around the world and work odd hours. Submarine officers often struggle because they may go weeks to months without seeing any natural light.

“The Navy knows that the nature of the military disrupts biological clocks,” she says. “This is crucial because of its impact on brain function and peripheral systems.”

The research zeroed in on the prebiotic classification of foods. While there’s been a good deal of attention paid to the value of probiotic foods, studies of the role of prebiotics is somewhat newer. Prebiotics are naturally abundant in many fibrous foods. Undigestible carbohydrates that pass through the small intestine, prebiotics linger in the gut, nourishing helpful colonies of bacteria that reside there. Foods that are rich in prebiotics include leeks, artichokes, and onions, among others.

Fleshner and her team investigated whether a diet high in prebiotics could make the body more resilient to the physical effects of acute stress. Their previous research suggested the answer would be yes, but the new study took that question to the next level.

And the results were promising.

“This work suggests that by promoting and stabilizing the good bacteria in the gut and the metabolites they release, we may be able to make our bodies more resilient to circadian disruption,” Fleshner says.

To find out, the researchers fed rats diets made up of normal amounts of nutrients, or one enriched with prebiotics. They then manipulated the rats’ light-and-dark cycle weekly for 8 weeks, equating to traveling to a time zone 12 hours ahead, weekly, for 2 months.

They discovered that the latter group hosted an abundance of two specific microbes that produced metabolites protecting them against the circadian disruptions common to jet lag.

Looking Ahead

As promising as the first study results were, more research is needed, including human testing. Clinical trials are underway to determine if a prebiotic-rich diet could benefit humans as well.

That said, “to reach the equivalent amounts of prebiotics via diet in humans really isn’t possible,” says Fleshner. “We can’t define the amount exactly right now, but it’s enormously large.”

While the rats in the study were able to get to an impactful level of the helpful gut bacteria relatively quickly, the same may not be true for humans. Fleshner says the thinks humans would need to start increasing prebiotic intake several days before they might need them. This could be a few days before travel, for instance, or before going on a week of swing shifting.

So could a prebiotic-rich diet get humans to the levels they’d need for meaningful benefit against circadian disruption?

“The dream, obviously, would be to pop a pill and avoid sleep disruptions, but we’re a long way from that right now,” Fleshner says. .

One more way to beat the effects of circadian disruptions could potentially be adding exercise to the mix.

“Our guess is that diet alone can help, but we wonder if adding exercise could bring a bigger bang for the buck,” Fleshner says. “This could lead to a more global effect on the helpful gut microbes. It’s something we’d like to study in the future if we can get the funding.”

While that’s encouraging, there’s a long way to go before the preliminary research can offer prescriptive advice, she says

“We don’t know yet what -- or if -- there are human dietary recommendations to apply to circadian disruption,” she says. “But the take-home is that in medicine, we can begin to think in terms of the contributions these gut bacteria can make to health and wellness.”

Show Sources

Monika Fleshner, professor of integrative physiology, University of Colorado Boulder.

CU Boulder Today: “Better sleep? Prebiotics could help.”

Brain, Behavior, and Immunity: “Ruminiclostridium 5, Parabacteroides distasonis, and bile acid profile are modulated by prebiotic diet and associate with facilitated sleep/clock realignment after chronic disruption of rhythms.”

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