A stressful lifestyle, busy schedule and lack of sleep are known to cause dark under-eye circles — but they aren’t the only possible reasons. Other factors such as genetics, dehydration and age, can also cause them to form, making them uniquely challenging to treat. “Dark circles result from under-eye puffiness, volume loss, hyperpigmentation and visibility of the blood vessels in the under-eye area,” says Dr. Marisa Garshick , a board-certified dermatologist at MDCS Dermatology in New York