I have bouts of 2-7 hours about once/year with very high pulse and always end up in ER via ambulance. The pattern you describe seems to point to some sort of trigger. I will not wear an Apple watch for the reason you describe (I am sensitive to EMF). I use a Kardia device. Mine are also at night and I stop eating at 6pm, which has helped. As I wrote elsewhere, there are vagal and adrenal afibs, and one of them does not do well with beta blockers. I will try to find the info. I use diltiazem as needed, so once a year, and nothing else so far.