A new study suggests that insomnia might be linked to the bacteria living in your gut. Researchers found that certain gut bacteria may raise the risk of sleeplessness, while others may help protect against it. People with insomnia tended to have fewer “good” bacteria and more of the types linked to poor sleep.

The study looked at genetic data from nearly 387,000 people with insomnia and gut bacteria data from 27,000 others. Experts think these microbes may affect sleep by changing brain chemicals like serotonin and dopamine, as well as by influencing inflammation and the immune system.

While more research is needed, the findings could lead to new treatments, such as probiotics, prebiotics, or other ways to improve gut health. For now, it’s another sign that what happens in your gut may be closely tied to how well you sleep.