Can birth control make you sleepy.?

I am on the generic form of the birth control pill and I sleep all the time. I can't stay up past midnight. I'm lucky if I can nowadays, but I use to be able to stay up really late and wake up at seven or earlier, but I take naps in the daytime. I used to not take naps and go to bed later and wake up early but since I started the pill all I want to do is eat and sleep. Is this normal? Why does this happen?