Ask the doctor: Baggy eyes
Q. What causes bags and puffiness around the eyes and dark circles underneath them?
A. Gently pinch the skin under your eyes and give it a little tug. You'll feel that it's a little looser and thinner than skin elsewhere. As we age, some of the fat under the skin of the face disappears and gravity tends to pull what's left downward. Bags form under the eyes partly because there's less fat supporting the skin, so it becomes slacker. Thinner and looser skin also allows fluid to collect, causing a puffy appearance. The dark circles — not true circles, of course — under the eyes are caused by blood pooling in the veins just under the skin. The skin there is especially sensitive to sunlight, so some of the darkness may be from pigment. You've probably noticed the puffiness around your eyes after you first get up in the morning, and the dark circles may be more visible then, too. You're seeing the consequences of being in a horizontal position, which creates a greater tendency for fluids to accumulate around the eyes and for veins to expand (dilate) so they hold more blood.
If your eyes get noticeably puffier and the puffiness doesn't go away, you should consider seeing a doctor. Puffy eyes can be a sign that you're retaining fluid, and fluid retention can be a symptom of serious kidney, heart, or liver disease. Similarly, if your eyes got puffy after you started a new medication, you should talk it over with your doctor. You may be having an adverse reaction.