You are likely on this site because you are suffering from one or more of these ailments.
This is probably the most common. People suffering from it are often prescribed a softer mattress to alleviate pressure points. Before you trash your perfectly good mattress and buy a soft one perhaps we can strategize a foam topper for your mattress.
You were told that sleeping on your stomach is a bad idea. You are doing this anyway because you are used to it or because you like it or because this is the only comfortable position. You get uncomfortable after a while because the front of your body is more heat sensitive.
Sweaty balls or hot flashes
Depending on your gender and age your are feeling one of these. You toss and turn or just wake up from feeling hot.
Your skin is too sensitive to heat, in addition to a whole bunch of common chemicals.