1. The sweating: What do you keep the thermostat at during the night? Sleep experts recommend setting your thermostat to 66'F. Yes, I know that seems like it'd be FREEZING, but it's truly better to be able to cover ourselves and breathe the cool air. If it's warmer than 68'F, it's too warm for sleeping.
2. Bruises: My kids are always bruised on their legs. They're klutzy and bonk into things. It's normal.
ETA: 76'F is WAY too warm for sleeping! WOW!
I suggest turning the thermostat down. Start with dropping it to 70'F tonight so the difference doesn't cause sleep issues. But I think that even that much will help soooo much.
I'd leave it at 70'F for a week, and then drop it again to 68'F the next week.
I bet everyone will sleep so much better and DRYER.