According to some researches, the lack of sleep is the main reason of the appearance of the dark circles. But there are some other factors also like allergies, nasal congestion and genetics.
Anemia, eczema, stress, sleeps deprivation, crying, too much sodium, smoking, oversleeping, sun exposure, mononucleosis and aging can also be the trigger for dark under-eye circles. Sometimes, dark circles could be an indicator of some serious health problem, such as liver disease or hyperthyroidism.
There are many cosmetic products which offer cure for this problem, but in fact, most of the products are not effective and expensive.
The baking soda is very popular these days and it is used in many recipes for beauty. You should try this recipe because baking soda is effective and cheap. Also, baking soda has proven to be effective like conditioner, shampoo and facial mask against acne.