What are the disadvantages of drinking too much coffee during menstruation?

I thought I got an easy job, but it turned out it wasn't. As a result of the need of work, can sleep very late at night, often drink some coffee to refresh, but recently began to menstruation, I am worried that drinking coffee will affect menstruation, what bad effect will drinking coffee have on the body after menstruation? Coffee is a kind of stimulating drink, but it is actually flat.