All 3 of my kids have dark circles despite sleeping good. My oldest has 23 confirmed food allergies + 3 enviromental + 1 pet allergy. My middle child has GERD.
My baby has a few confirmed food allergies atm (corn/dairy/grapes/pork, a few others).
Their iron has been checked, they're all good on that.
Could the dark circles be due to food allergies?