Omg....I'm keeping a journal since 2019 and I document "vibrations with pauses". I rate them on scale 1-10 and if they are like a 3 or 4 I can usually go back to sleep. If they are above that, I have to get up before they stop but yes it's so weird because the pauses coincide with your heartbeat. PLEASE isn't there somebody out there that's willing to take on this challenge to help find out what these internal vibrations are?
I didn't receive covid shot, ever. So they can start and rule out things. There HAS to be a common factor.
It's the vibrations that wake you up so there's really no telling how long they were going on before you actually wake up. I thought one of my cats jumped on the bed one night and I woke up and realized it was me vibrating. I had to get up they were at a level 10. They happen only AFTER I have been asleep.