PNNL

The human gut contains millions of microorganisms, including hundreds of different species of bacteria. This collection of microorganisms that live in and on the human body is called the microbiome.

New research from Pacific Northwest National Laboratory and Washington State University collaborators connects the microbiome in the gut to circadian rhythms, suggesting the microbiome plays a role as an internal regulator—another clock that works in tandem with the central clock in your head.

What happens when an internal clock can’t tell time?

Disruptions to circadian rhythms can have significant effects on health and well-being. For example, jet lag occurs when a person rapidly travels across time zones, causing their internal clock to be out of sync with the new light-dark cycle. This can result in symptoms such as fatigue, difficulty sleeping, and impaired cognitive function.

Shift work, which involves working outside of the typical day-night schedule, can also disrupt circadian rhythms and lead to similar issues. Approximately 20 percent of U.S. workers perform shift work, which leads to frequent circadian disruption, increasing the risk of developing a variety of diseases.

“It is crucial that we understand which functions of the microbiome are rhythmic, how these rhythms interact with the host, and which are subject to manipulation, so that we can develop robust intervention strategies for those whose occupations require atypical sleep schedules,” said Chathuri Kombala, a PNNL scientist and first author of the research article, which appeared in the journal Organic & Biomolecular Chemistry.

Trust your gut to regulate

When you engage in an abnormal sleep-wake cycle, you also disrupt eating patterns. This in turn disrupts the behavior of your gut microbiome. The microbiome is already known to regulate several processes in the human body. This study has linked the rhythmic activity of gut bacteria to the internal clocks in your body. Previously, regulation of circadian rhythms by the gut microbiome was poorly understood, as well as being costly and time-consuming to study. The research team can now effectively measure gut microbiome activity.

Using a feeding pattern associated with shift work for the experiment, the team developed an easy-to-read test that did not require multiple time points for collection and used only a small fecal sample. To enable this, the research team had to detect certain molecules produced by bacteria in the gut, and they did so by developing a novel test that was able to produce results 30 times faster than previous studies, with 20 times less fecal sample amount required. This replaces prior extensive sample processing, long testing time, and complex experimental setups. Scientists are still exploring the complex interactions between the microbiome and health risks associated with disruption of circadian rhythms.

Keep both clocks in sync

Overall, circadian rhythms play a vital role in regulating numerous physiological and behavioral processes. Understanding and maintaining synchronous harmony of these natural rhythms across the body can contribute to better overall health and well-being. The field of microbiome research is rapidly evolving, and scientists are continually discovering new insights into its importance for human health.

“Based on our observations we believe that a function-focused analysis of diurnal rhythmicity of the gut microbiome in general is needed to understand the impacts of rhythmic processes in the host,” said Kombala.

The work of these researchers gets us closer to that understanding of physiological rhythms. They have demonstrated a new, simple, and efficient tool to detect and quantify enzyme activity in complex biological samples. This new understanding of microbiome rhythmicity has the potential to aid in the discovery of therapeutic, diet, or lifestyle interventions for correction of circadian perturbations linked to gut microbiome metabolism.