Irregular sleep patterns are linked to increased levels of harmful gut bacteria. The corresponding study was published in the European Journal of Nutrition.
Previous studies show that working shifts disrupts the body clock and can increase the risk of weight gain, heart problems, and diabetes. Less is known, however, about how smaller shifts in sleeping patterns, such as different waking times between weekdays and weekends, affect gut bacteria. These time discrepancies are known as ‘social jetlag’.
In the present study, researchers set out to see how social jetlag affects gut bacteria. To do so, they analyzed data from 934 participants, including their demographics, diet, cardiometabolic measures, stool samples, and self-reported habitual sleep habits.
Overall, 16% of the participants, or 145 people, were characterized as having 'social jetlag': a minimum 90-minute difference in the midpoint of sleep, or the halfway point between sleep time and wake-up time. 'Social jetlaggers' were more likely to be male, have a shorter sleep duration, and be younger than those with more regular sleep routines.
Ultimately, the researchers found that the social jetlag group was more likely to have higher levels of three gut bacteria previously classed as having an ‘unfavorable’ impact on health, including an increased incidence of indicators of obesity, lower cardiometabolic health, higher levels of inflammation, and higher cardiovascular risk.
The researchers noted that having social jet lag was linked to lower dietary quality with higher intakes of sugar-sweetened beverages and lower intakes of fruits and nuts. They further wrote that the three 'unfavorable' bacteria identified in participants with social jetlag have also been linked to poor diet quality.
Senior author of the study, Dr Wendy Hall from King's College London said in a press release: "We know that major disruptions in sleep, such as shift work, can have a profound impact on your health. This is the first study to show that even small differences in sleep timings across the week seems 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," she added.