Researchers find that salivary microbiome exhibits
circadian rhythm

A group of Japanese researchers became the first in the world to discover that bacteria in the salivary microbiome exhibit circadian rhythm and act as if it were a part of the human body, just like organs and cells.
A circadian clock of a 24-hour cycle exists in most organisms including humans, adjusting the circadian rhythm to control various biological functions which occur during the day and at night. The circadian clock transmits information to cells and organs in the body from the brain and sustains the organism’s health. Until recently, circadian rhythm was a phenomenon only observed in cells and organs of organisms, but the researchers found that it also exists in  the microbiome of saliva.

This research is published in DNA Research.