Inadequate sleep,sleeping for long hours, rubbing your eyes and smoking are some of the unhealthy habits that cause dark circles
Age is another prominent factor that leads to loss of fats which creates depression around the eye region to cause dark circles.
Working for long hours in front of the computer screens can strain your eyes which enlarges the blood vessels surrounding the eye region and causes the thin layer of skin around the eye to darken.
Allergic reactions can trigger the blood vessels near the eye region to dilate. As mentioned earlier that the skin in this region is the thinnest, the dilation can lead to dark circles.
Believe it or not, your genes can also be responsible for your dark circles. Hereditary dark circles run in the family for generations and get passed on. So if your parents or grandparents have dark circles then chances are that the darkness around your eyes is a Hereditary dark circle.