Caffeine alternative

Does anyone know of a safe alternative to caffeine that can help as an alternative stimulant during pregnancy? I'm ADD and obviously cannot take my medication while pregnant. The meds and coffee have always helped with getting through the work day but now I'm struggling to concentrate at work. (Worth it, of course, for a healthy baby!) I am trying to get 7-8 hours of sleep each night to help but I have a hard time sleeping as it is. Any suggestions to keep me alert during the day? Thank you!