Are you taking it in the morning or night? I was thinking switch the time of day you take it and see if when it peaks in efficacy (sp?) might help with when the insomnia hits. Maybe try a natural sleep aid like melatonin before going to sleep?

I had the opposite problem on Lexapro. My p-doc said I was one of the handful of patients she'd had on Lexapro that turned into Rip van Winkle. I couldn't stay awake more than two hours (really!) and was sleeping 15-18 hours a day. I had to switch to Zoloft which has been a better fit. But I know Lexapro does work for many people. My mom has taken it for many years. She told me it generally takes about 4 weeks to settle in with it. I hope it works out for you soon and that you can get sleep soon.