My husband has recently been put on Lexapro and goes between feeling very tired to feeling like he can't sleep. He has also told me he will sometimes have a hard time concentrating and a few times he has felt like he just can't sit still. So, it is very much likely due to the Lexapro and not the birth control. I'm not a professional, but it is likely your body adjusting to the medication. Hang in there until your doctor gets the right dose!