I am 18 years old, 5"2, and pregnant weighing 160lbs. (however this has happened prior to pregnancy) I've noticed when ever I wake up my chest and lungs feel like ICE inside, they get super cold and it becomes harder to take a breath. Plus with each breath is makes them feel colder. Not a big deal, it's been happening for as long as I can remember and I'm still here. However, I'm curious as to why. The problem subsides after I sit up or get out of bed.