Low HR this month

I got my first low heart rate warning on my Apple Watch this morning, that it dropped below 45bpm for 10 minutes while I was sleeping. I’m on bisoprolol and I have noticed this month it’s been really low but I’m on summer vacation (teacher) so I have been able to relax and basically do nothing so I’m wondering if it’s cause of that?? I have been able to work out and go on walks and such so maybe that’s helping too? I am worried about it being so low🙃