Sleeping in Over the Weekend May Be Hurting Your Gut Health, Study Finds

After a long week of waking up at the crack of dawn to get to work on time or the kids out the door, the only thing anyone wants to do is sleep in on the weekends. But as good as it feels, catching a few extra hours of shut-eye on Saturday and Sunday mornings isn't actually the best sleep habit for your health. In fact, it could be wreaking some havoc on the health of your gut microbiome, according to new research. 

A study from King’s College London, published in the European Journal of Nutrition, found a link between irregular sleep schedules and negative gut health consequences. Even seemingly small shift in sleep patterns, like waking up early by an alarm clock during weekdays and waking up later naturally on weekends, can impact biological rhythms and metabolism—and potentially even negatively alter gut bacterial species.

The study, comprised of nearly 1,000 adults, compared the blood, stool, and gut bacteria of participants who kept regular sleep schedules (i.e. they went to bed and woke up at consistent times every day of the week) and those who did not. 

"Researchers found that just a 90-minute difference in the timing of the midpoint of sleep—the halfway point between sleep time and wake-up time—is associated with differences in gut microbiome composition," reported King's College London on the study.

"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," said the study's senior author Wendy Hall, PhD, reader in nutritional sciences at King's College School of Life Course & Population Sciences.

The research noted that having social jet-lag—the shifts in our personal circadian rhythms when our sleeping schedules fluctuate between workdays and off-days—led to less gut-friendly diet choices, such as more sugary drinks and fewer fruits and veggies, which can impact the microbiome significantly. In fact, many of the markers in these socially jet-lagged participants were markers for negative health outcomes such as inflammation, metabolic health, and cardiovascular risk.

"Some of these associations were linked to dietary differences, but our data also indicate that other, as yet unknown, factors may be involved," Hall said. "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." 

So, what does this mean for the average person? For the sake of your internal body clock and healthy gut bacteria, try to wake up at the same time every day of the week, as often as you can (or at least not to change your routine up too much). The more regular your wake-up time, the better your body will become at getting tired and falling asleep at the same time each night. Keep a consistent bedtime routine, a favorable sleep environment (comfy, extra-dark, and cool), and watch the afternoon caffeine to help you sleep better.