I just started on 50 mg dose of naltrexone to reduce alcohol intake. My first two days I was instructed to only take 1/2 pill. My first 1/2 pill dose was last night and I had a terrible night's sleep, with a pounding heart and head. I suspected that my blood pressure was spiking, and thought maybe I'd forgotten my daily dose of Valsartan, so I took another BP pill at 1 a.m. Tossed and turned still, but got some sleep. Took my blood pressure this morning and it was high-normal, which is normal for me. What happened? Is this typical for someone new to naltrexone?