Why do I get so hot while sleeping?

Lots of people do this. My husband is the same way. He has to sleep with a light, thin blanket even in Winter because he will sweat like a pig and become boiling hot! Some of us do not regulate our internal heaters well during sleep. Unless you're waking up literally in a pool of sweat, no need to worry about it. If you are sweating profusely you then should see a doctor for a check-up, but usually this is nothing to worry about.