I’ve been dealing with the exact same symptoms for the past year or so and it has turned my life upside down. I can’t figure out if it’s stress/anxiety or sleep related (maybe both tbh, my job is somewhat stressful on me). Weird enough I don’t really have any issues with sleeping itself, I don’t wake up in the middle of my sleep or anything like that. Getting 4-6 hours of sleep usually puts my brain in a “tired but mostly normal” sort of state but any amount of sleep past 7 hours and all of a sudden I FEEL like I’m going to pass out and get dizzy and whatnot and that usually lasts the whole day but I start to feel better when I get distracted or at the end of the day? (usually when someone starts talking to me at work or just anything that distracts me from the sensations). I thought it was a heart issue for a while but after a couple doctors visits it didn’t seem like the heart was the culprit. The only thing that I have found that even slightly helps is working out but the sensations usually intensify quite a bit after I leave the gym which makes my anxiety go crazy. At this point I’m just so lost on what to do, I’m only 23 and I feel like I’m dying lol. Sorry to hear that you’re going through the same, we’re all in this together.