The only AP I've had is Seroquel. To me it feels like there's something really heavy pressing on my mind, like a physical weight, pulling me down. It's more than just regular tiredness. More like I took a sledgehammer to the head or something. It can also make me really loopy, make me think weird things and say weird things that I normally wouldn't. Usually it's worst after waking up, but sometimes it lasts all day.