Staying Up Late On The Weekends May Harm Gut Health, New Study Shows

We can live very different lives during the same week. A weekday version of you may go to a 9-to-5 office job, hit up a yoga class after work, and be tucked into bed at a reasonable hour (so you can do it all again tomorrow). Whereas weekends you may have a more sporadic schedule filled with social events that keep you up late. 

But even if you're getting the same (or possibly even more) sleep on the weekends, shifting your sleep schedule back from your norm may negatively impact your gut microbiome. A study1 published in the European Journal of Nutrition is one of the first to try to understand this relationship. 

Researchers out of King's College London used a survey to collect information about sleep from 934 healthy (primarily white) adults. Questions such as "What time do you usually go to bed?" and "What time do you usually wake up?" were captured for both weekend days (Friday-Saturday) and weekdays (Sunday-Thursday). 

Based on those answers, those who had a later sleep time on the weekends by at least 90 minutes were deemed as experiencing "social jet lag" (aka living according to a social clock versus a circadian clock).

Now, this weekday/weekend sleep discrepancy gets the name social jet lag and has been studied and flagged as a potential link to health concerns like metabolic dysfunction and mood disorders2. But not much is known about how it impacts the gut microbiome. 

Past studies show that altered sleep patterns by night-shift work also disrupt healthy gut function3. And while that's obviously a much larger change in sleep and wake times than a late Friday night dinner affecting your bedtime, it's still possible that seemingly small sleep changes can affect health. 

Although only 16% of people in this study met the criteria for social jet lag, there were noticeable differences between the gut microbiomes of both groups. And those in the social jet lag group had a higher prevalence of three unfavorable microbial species. 

However, late nights are also often accompanied by other not-so-desirable habits. And those in the social jet lag group had a poorer diet quality (eating higher-calorie foods and less fiber, fruits, and vegetables).

Surprisingly, eating nuts helped counter some of the negative changes to the gut microbiome. Information on alcohol intake was also collected, but even after it was accounted for, it didn't change any of the study's findings.