Why do I get these symptoms but only when I'm tired?

I'm sleep deprived (being a high school student and all) much more often than I would like. I've noticed a few things happen when I'm tired that seem to happen to nobody else and the internet seems to have no clue about it. When I'm tired I always get really thirsty and pee more frequently. I'm not diabetic because this only happens when I get like less than 4 hours of sleep. If I get more I drink a perfectly normal amount, maybe less, but when I get too little sleep I drink all day. Is it because I drink more caffeine when tired? It seems a little extreme for a little extra caffeine. I also notice I can sort of feel a blunt something where my kidneys are. It's like I can feel my kidneys are there. It's not pain, I can just feel them there putting pressure on my whatever kidneys are attached to, like they're heavier than usual. Those are the two weirder ones. My eyes start to vibrate and shake a little, but I think that isn't too weird. Any idea why I get so thirsty when tired? Is this normal?