This may seem stupid to ask but I am on O2 at night and was advised to also use during increased activities. My question is this, since COPD causes difficulty exhaling, are the lungs still able to absorb (for lack of better word) the oxygen and utilize it throughout the body? Wouldn't it increase the risk of trapped air since exhaling is obstructed? My PCP always asks if the nighttime O2 helps me feel more rested and honestly I feel no difference. Any thoughts?