Yes, of course, stress can cause dark circles under your eyes. as we know that when you are stressed, it can lead to the disorder of your body. In some degree, it can affect the eyes. Also, stress can make you have bad rest and sleep. In that way, it can lead to dark circles. To treat them, the first thing you should do is to keep relaxing. As we know that relaxing might help remove sources of stress and anxiety that are preventing you from sleeping, eating and resting properly. So that it can relieve the dark circles. Also, cucumber slices have long been used to reduce puffiness and refresh the appearance of skin around the eyes, providing a fast "pick-me-up" for tired and puffy eyes. But on the other hand, they can also be good for the dark circles. So just put a slice over each eye, extending over the darkened area. Remember that you should do this everyday, coupled with lying down for 10-15 minutes. Anyway, you can have a try.