The short answer to this question is that everyone has pressure points. Pressure points are just the areas where your body presses down on the bed, depending on how you sleep.
Pain can occur in these areas if you sleep on a mattress that doesn't work for your sleep style and body type. Overly firm mattresses are the most common cause of pressure point pain, though too-soft mattresses made of materials that can't contour can cause pressure point issues as well.
Most of the time, finding a mattress or mattress topper that better fits your sleep needs can fix the problem. For example, if you have a medium-firm mattress but are a side sleeper, you'd need to either find a plush mattress topper or replace your mattress with a medium-soft or soft mattress.