My 80 Year Old Father Who Had A Quadruple Bypass

My 80 year old father who had a quadruple bypass in august was just prescribed trazadone for sleep issues. He is complaining of anxiety and feeling twitchy when he wakes at night to urinate or from apnea issues. HE is able to fall back to sleep, but the anxiety is upsetting him. IS this normal...will it go away as he adjusts to the med. He has never taken psychotropic med before.