Gut Bacteria Differ In Morning, Night People: Study

Do you consider yourself a morning lark or a night owl? A team of researchers found distinct differences in the gut bacteria of these chronotypes.

People can have vastly different sleep patterns, the authors of a recent study said, noting that early risers and late sleepers are examples of people who have opposite chronotypes.

However, being a morning or a night person doesn't just affect the time of the day when people are most alert. There has also been evidence that having a late chronotype can impact one's risks of developing conditions such as mood disorders and diabetes.

In their study, the team of researchers had a closer look at the composition of the gut microbiomes of people of various chronotypes.

"Despite the vast potential of utilizing chronotype information for precision medicine, those factors that shape chronotypes remain poorly understood," the researchers wrote.

"It is already known that there are some genetic differences between larks and owls, but research in fruit flies in our laboratory inspired us to test the impact of gut bacteria on human chronotypes," Prof. Eran Tauber, study head, said in the news release from the University of Haifa.

To do this, they sequenced the bacterial DNA of the fecal samples from 91 people from across Israel, 50 of whom were female. Their chronotypes were determined based on their self-reported sleep times without an alarm clock in the weekend, revealing that 24 of them were deemed to have the "early" chronotype. Meanwhile, 27 and 40 had "intermediate" and "late" chronotypes, respectively.

They found two genera that were "significantly different" between the early and late chronotypes: the Alistipes and Lachnospira.

"Within these genera, two species were significantly different between groups," the researchers wrote. "Alistipes putredinis was more abundant in the early chronotype, as compared to both the intermediate and late chronotypes. Lachnospira pectinoschiza was more abundant in the late than in the early chronotype."

Interestingly, Alistipes has been reported to be more represented in older mice and humans, supporting the notion that chronotypes become earlier with age. Moreover, in a previous study, Lachnospira was found to be more abundant when "a greater percentage of energy was consumed after 2 p.m.," the researchers noted.

"This finding aligns with our data portraying Lachnospira as a biomarker of the late chronotype, as energy consumption is expected to be delayed in these individuals," they wrote.

When the researchers looked at the diets of the different chronotype groups, they found that those with the early chronotype had a higher consumption of water, fruits and vegetables, while simple sugars and high protein were "prominent" late chronotypes' diets.

As the university explained, this difference may also "underlie" the differences in people's gut bacteria. With night owls who need to work or go to school early tending to experience health issues including obesity and high stress levels, such information could prove helpful in developing possible interventions.

"Our work demonstrates an association between the gut microbiome and chronotype and may represent the first step towards developing dietary interventions aimed at ameliorating the deleterious health correlates of the late chronotype," the researchers wrote.