IBS—or Irritable Bowel Syndrome—can be a mysterious ailment. Its yucky symptoms seem like an unpredictable stomach bug.

But researchers are better understanding its causes. A new study links the bowel disorder to overgrowth of bacteria inside the gut. Lowering stress can also help symptoms, so this optimistic news is a double sigh of relief!

MORE: Calming Your Mind and Gut for IBS relief