You could just be really healthy, when I was in the navy my resting was 43, who knows what it was asleep. Water fasting these days is (should be) not just water but with high grade salts (google the correct ones) I just buy the snake juice packets on Amazon for super convenience. 1 packet every 1-2 days is sufficient. While fasting you’re body (I mean your mind speaks to you more) you’ll feel and see and hear better but also and switch to listening to your heart beat and can by anxiety inducing cause you’re like woahhh I can hear my heart am I tripping??? But no it’s kinda like choosing to breath actively, you can choose to activity feel or hear your body” and it’s not something that’s studied in medicine yet unfortunately- thanks money only going to specific studies that only benifit pharma