Unisom is OTC, and I believe they make a disolvable tablet form if you have trouble swallowing pills. It is generally considered safe during pregnancy, but you might give your OB a call just to double check.
And, let me assure you, that having a cute baby to look at will not keep you from wanting to murder your husband as you watch him sleeping peacefully while you're up nursing a newborn 5 times a night :)