Dark circles are caused by various reasons. One is bad blood circulation. Skin around eyes is thinner so that the shadow is easy to be seen. Another is lack of sleep, which is the normal reason for mostly people. Fitly, the shark liver oil contains the essence of vitamin A and other nutrition which are effective for health and promote the circulation of the blood. Therefore, it can really do work for the dark circles. However, the most entitative reason give rise to this situation is your unhealthy habits.Hence, you'd better get enough rest, keep a healthy diets as well as exercise everyday. Besides, eyes massage and mild hot compress will also helpful. Hope you can get rid of this situation soon.