Studies link insufficient sleep to some pretty scary consequences, including an increased risk of stroke, heart disease, diabetes, obesity and even some cancers.
Experts still don't fully understand why not getting enough sleep is connected to all of these conditions, but new research published this month adds one piece to the puzzle: Not getting enough sleep may cause changes to gut bacteria that could fundamentally change our metabolism, affecting a host of bodily systems.
Gut microbiota are the trillions of microorganisms living in our intestines that help keep our metabolism, immune system and other bodily functions running normally, explained senior study author Jonathan Cedernaes, a sleep researcher at Uppsala University in Sweden. Mounting evidence has linked an unhealthy gut microbiota with inflammatory bowel disease, allergies, neurodegenerative diseases and metabolic diseases including obesity and diabetes.
This new study is one of the first to suggest that not getting enough sleep is one way of making our gut bacteria unhealthy, Cedernaes explained.
Restless nights throw our bacteria out of whack
The researchers followed nine individuals who spent two nights sleeping in a lab for eight and a half hours, and then another two nights of sleeping in a lab for only four and a half hours.
The study included a fairly small number of people, but the strength behind the data is that the researchers were able to compare the effects of varied sleep levels on gut bacteria within the same individuals. Plus, they only included subjects who reported having gotten consistent sleep and regularly timed meals the week before the study, which meant everyone's gut bacteria started out at a somewhat typical level.
The data showed that getting less sleep didn't necessarily change which gut bacteria the individuals had. But getting less sleep did change the levels of specific strains of bacteria. The amount of certain types of bacteria decreased by nearly 50 percent ― and that was after only two nights of not getting enough sleep.
The finding was significant because the wrong balance of bacteria in our gut is thought to be one of the big factors that cause obesity in some individuals, Cedernaes explained.
Gut bacteria are a crucial, natural component of our bodies. Jonathan Cedernaes, a sleep researcher at Uppsala University
What's more, the ratios of specific strands of gut bacteria observed after individuals had not gotten a full night's sleep mirrored the levels of the same gut bacteria previously observed in people who were obese or had other metabolic diseases.
"Gut bacteria are a crucial, natural component of our bodies," Cedernaes said. "[They] break down fibers that we cannot digest otherwise. They can also help us extract nutrients."
There was yet another interesting finding from the study. The individuals were 20 percent less sensitive to the effects of insulin after having less sleep ― a potential diabetes risk ― compared to the days after the nights they had slept longer.
Sleep loss has been linked to decreased insulin sensitivity in previous studies, Cedernaes said. And while his new research did not necessarily suggest the effect was a result of the gut bacteria changes, the link is still an important observation because over time, constant insulin insensitivity is a well-established driver of diabetes.
Additional, longer studies will be necessary to prove that the gut bacteria changes observed after a few nights of insufficient sleep are linked with the various metabolic diseases thought to be connected to chronic sleep loss, like obesity, diabetes and heart disease. But the new data makes a strong case, Cedernaes said ― a strong case for catching your Zs.