Getting a good night’s sleep may be about cultivating healthy gut bacteria, not counting sheep.
The importance of gut health has only become clearer over the last few years. The Human Microbiome Project introduced the world to the trillions of bacteria that live on our bodies—many of which are found in the gut—and impact human health in huge ways, and a wide variety of recent studies have suggested possible links between poor gut health and obesity, depression, autoimmune diseases, and much more.
So it only makes sense that the community of microbes in your digestive tract, which are heavily dependent on your diet, may also be influencing how well you sleep at night, and vice versa.
“Recent evidence indicates that what you eat and when you eat can in turn affect sleep and circadian rhythms,” says Phyllis C. Zee, MD, PhD, the director of the Center for Circadian and Sleep Medicine at Northwestern University’s Feinberg School of Medicine, who says emerging research “points to a bi-directional relationship.”
The circadian clock plays a huge role in determining when you fall asleep and wake up, since it regulates your sleep-wake cycle using cues from the environment. It tells your brain to release the sleep-inducing hormone melatonin, for example, in response to darkness.
Circadian rhythms have been linked to other processes in the body like metabolism, and new studies suggest they could also be linked to the gut microbiome.
“There is evidence that the gut microbiome also has circadian rhythms and cycles,” Zee explains. “When healthy, its rhythm is regulated and in sync with the brain’s clock that regulates the timing of melatonin secretion.” Think about it: The brain and gut are inextricably linked via the nervous system, and you don’t want two best friends who rely on each other to be operating on completely conflicting schedules.
Functional medicine physician and Parsley Health founder Robin Berzin, MD, adds that poor gut health can also disrupt sleep since it causes inflammation, which does not stay local but affects multiple systems. “When people stop eating foods that are triggering their immune system [resulting in an inflammatory response], they have a much easier time sleeping,” she tells Yahoo Health.
Meanwhile, Berzin adds, if you’re sacrificing hours of sleep to hit a deadline at work, that could have a negative impact on your gut bacteria and digestion, since sleep deprivation affects neurotransmitter receptors in the gut. Plus, being overtired does not generally lead to food choices your microbiome will appreciate.
“When you don’t get enough sleep or when your clock is out of sync with sleep or work schedules, there are negative effects on metabolism and glucose control, as well as [effects on] the types and amount of food you consume,” says Zee. “Lack of sleep or late eating makes one crave more junk food. Not salads!”
Here’s what you can do: Both MDs say seven to eight hours of sleep a night is a must. Zee also recommends regular exercise, having light exposure during the day, and sticking to regular sleep, wake, and meal times (and not eating dinner within three hours of bedtime).
In terms of feeding your microbes for good gut health, New York City nutritionist and Foodtrainers founder Lauren Slayton, RD, says taking probiotic supplements and adding fermented foods like “kefir, fermented vegetables (not just kimchi), fermented hot sauce, and miso” to your diet are first steps. “It’s not just about adding fermented foods but also watching sugar and refined (AKA ‘white’) carbs,” she adds.