I saw this on an apple forum and wanted to see if this resonates with anyone here. I bought the newest apple watch series 9 and had to return it.
I picked up my watch around 7 pm, and went to sleep with it immediately after buying it. After I woke up the next day (8 hours later), I fainted for the first time in my life. I stayed off of the apple watch for 2 weeks to see if it was anything else health related (saw a bunch of doctors for retina/neurology/primary) and all health visits were fine. I put it on to try it one more time after 2 weeks and within 5 minutes felt dizzy and like I had vertigo.
I reported this to apple but they had a really weird idea that I was using the watch too much which they can monitor by looking at screen time and seemed like a wild guess since I know I barely used it. Posting for awareness to see if anyone else has faced this.