Yes, when I sleep a long time and/or deep sleep, I get a sort of rebound effect. No headache when I wake but really “floaty-feeling” and then later I usually have more head pressure than usual. Like my body healed too much, or maybe it could simply be coming out of a deep fast. In my opinion its best to just stick to the normal 7-8 hour sleeping schedule with MAV.
I also got into insomnia trouble because I was trying to sleep too long, thinking my body just needed more sleep. This made me roll around and be anxious about sleeping, because I was just trying to sleep too much when I didn’t need to.