Disrupted Sleeping Patterns Are Associated With Harmful Gut Bacteria

A study has found that changes to our sleeping patterns – such as getting up early on weekdays and lying in on the weekend – are associated with the presence of harmful bacteria in the gut, as well as diet quality and inflammation. The research is published in The European Journal of Nutrition.

Social jet lag and the microbiome

The bacteria, viruses, fungi and other microorganisms that call our gut home are collectively known as the gut microbiome. Its makeup can have important implications for our health, as some microbes can aid digestion and secrete helpful metabolites, but harmful bacteria can also produce damaging toxins.

Our diets can significantly impact the composition of the gut microbiome, making it possible to adjust the diversity of the microbiome through what we eat. This influences the presence and abundance of different microbes that can impact our risk of long-term health conditions.

Previous research has shown disruption of the body clock – due to shift work, for example – can increase the risk of weight gain, heart problems and diabetes. Less is known about how our biological rhythms are affected by smaller changes in sleeping patterns, such as waking early on workdays and waking later naturally on non-workdays. This a phenomenon, known as “social jet lag”, has previously been linked to weight gain, chronic illness and mental fatigue.

To understand if irregular sleeping patterns could also be affecting our microbiome, researchers analyzed blood, stool samples and glucose measurements from participants of the ZOE PREDICT nutritional study. They compared data from participants whose sleep was irregular to those with a routine sleep schedule. This cohort consisted of mainly lean and healthy individuals, as previous studies investigating social jet lag and metabolic risk factors have been conducted in people with obesity or diabetes.

Changes to the gut microbiome

Researchers studied data from 934 participants of the ZOE PREDICT study, revealing that just a 90-minute difference in the “midpoint” of sleep – the point halfway between falling asleep and waking – was linked to changes in the composition of the gut microbiome.

Other factors were also found to be associated with social jet lag, such as low diet quality, high consumption of sugar-sweetened drinks and low consumption of fruit and nuts – all factors that may directly influence the composition of the gut microbiome.

Of six microbiome species found at higher levels in the social jet lag groups (with and without age matching), three are known to have “unfavorable” associations with health. These microbes are also linked to poor diet quality, indicators of obesity and blood markers of inflammation and risk of cardiovascular disease.

“We know that major disruptions in sleep, such as shift work, can have a profound impact on your health,” said Dr. Wendy Hall, senior author of the study and head of the diet and cardiometabolic health research group at King’s College London. “This is the first study to show that even small differences in sleep timings across the week seem to be linked to differences in gut bacterial species. Some of these associations were linked to dietary differences but our data also indicates that other, as yet unknown, factors may be involved. We need intervention trials to find out whether improving sleep time consistency can lead to beneficial changes in the gut microbiome and related health outcomes.”

The chief scientist at ZOE, Dr. Sarah Berry, added: “Maintaining regular sleep patterns, so when we go to bed and when we wake each day, is an easily adjustable lifestyle behavior we can all do, that may impact your health via your gut microbiome for the better.”

Reference: Bermingham KM, Stensrud S, Asnicar F, et al. Exploring the relationship between social jetlag with gut microbial composition, diet and cardiometabolic health, in the ZOE PREDICT 1 cohort. Eur J Nutr. 2023. doi: 10.1007/s00394-023-03204-x

This article is a rework of a press release issued by King's College London. Material has been edited for length and content.