I have them sometimes as well when I work hard and don't get enough sleep. Why don't you try to relax a little more and see what happens.
Dark circles under the eyes are temporary and caused due to insomnia, smoking, a family history of dark circles, deficiency of vitamin K in diet, allergies like sinusitis and eczema, and adrenal gland disorders.
Take rest adequately and eat healthy nutritious food containing lots of green vegetables. Try to avoid caffeine, because it promotes water retention and leads to the dryness of the eye. You should also apply almond oil or skin creams containing vitamin C or K, alpha hydroxyl acids and kinetin.
I hope it helps. Take care and please do keep me posted in case you have any additional doubts. Kind regards.