Can't Sleep At All!

I'm sure this is normal but I'm 16 1/2 weeks along and I can NOT sleep at night. I've started taking Unisom every single night in order to get some rest. If I don't, I'm extremely restless and don't sleep more than a few hours. Is it ok to take it every night? Also, has anyone been having HORRIBLE nightmares like me?! I woke up yelling and sobbing the other morning :(