I have only been taking Toprol xl 50mg. for a few days, but i not...

I have only been taking Toprol xl 50mg. for a few days, but i notice a difference already. (I take this to block migraines.) I feel out of it when i take this drug. I cannot sleep anymore! i cant fall asleep... and when i finally do, i am up a few hours later. I have been having weird dreams. (not about spiders, but other vivid, crazy dreams) Do you get used to the drug after a while and are able to sleep???? anyone know?? I have problems with anxiety and depression... and i think that lack of sleep would only add to that. I know that since i started taking toprol, i have mood swings like crazy. I will be happy and having a good time, then i will just switch and starting going off the handle. (about the littlest things too) So i ask, why do we take these drugs if we cant sleep, eat, think, have mood swings, etc???