What Causes The Ribcage To Hurt While Sleeping?

My ribcage sometimes hurts after a night's sleep and it's so overwhelming that I can't continue sleeping no matter how tired I am. The pain is relieved when I sit up, which is what I do when it really hurts even though all I want to do is sleep. I am 20 years old, 5 foot 4, and weigh around 105 pounds. This is not the first time this has happened.