Lexapro sedates me. I can't take more than a 10mg dose each day or I start sleeping 16+ hours. The lethargy mimics my depression cycle so it was hard to tell the difference when I originally started a 20mg dose.
Perhaps you have a similar reaction as me to lexapro?
My dr is using welbutrin to level the lethargy out because 150mg gives me energy but 300 makes me have a manic like episode if it's my only med at the time! (My dx is BP II)