Studies show that eating dark chocolate can be good for you and may contribute to improved cardiovascular health. It has a more pronounced chocolate taste than milk chocolate, because it does not contain milk solids Dark Chocolate Has Health Benefits Not Seen in Other Varieties of the chocolate:
dark chocolate ingredients include alkaloids that work as aphrodisiacs. These are theobromine and phenethylamine, which increase brain serotonin levels Dark chocolate is naturally rich in flavonoids (flavanols, a sub-class of the antioxidants).
Dark chocolate contains good cconcentration of resveratrol (powerful antioxidant that has been found good to protect the body from heart disease)
Cocoa wich is the main ingredient in dark chocolate contains a powerful antioxidant that protects against damage from free radicals and oxidation. Independent studies also  suggest that specially devised cocoa products including chocolates can work as cognitive enhancers and delay decline of brainfunction due to advanced age.
also dark chocolate is known to enhance the mood. it stimulates the production of endorphins, chemicals in the brain that bring on feelings of pleasure. It also contains the chemical serotonin, which acts as an anti-depressant.