Get plenty of sleep nightly

It's not entirely clear why inadequate slep results in dark circles under the eyes. For one thing it reduces circulation. A lack of sleep, coupled with poor vitamin absorption also tends to reduce adrenal function. The less adrenal function you have the less B6 you tend to absorb, the less B6 you absorb, the less well your adrenal glands work and alas you end up in a vicious circle. Good calcium/magnesium suppot in the form or milk or good mineral supplement restore adrenal function.