A Common Cold
If you've got the sniffles, you should expect to get some dark bags. "Dark circles can occur when you are sick if your sleep is interrupted and your skin doesn't have enough precious repair time," Batra said.
What's more, your prescription medication might be a sneaky culprit. One such example are vasodilators, or meds that treat high blood pressure. Unsurprisingly, these pills work to open vessels and increase blood flow throughout your body. While that's good for lowering pressure, it's bad for brightening your eyes.