Sorry if this sounds silly, but how low should a Beta blocker drop ur resting HR? I have been on bisoprolol 1.25 for two weeks (at night) and my Fitbit shows my heart rate is between 50 and 58 whilst I sleep. Resting HR during day is 62 but shoots up when exercising (140). Can BBs drop ur HR too low? Originally put on for tachycardia on exertion. Thank u.