I did a sleep study for oxygen at night and was borderline. My pulmonologist wants me to use at night. Said my 02 dropped a couple below 88, I am reluctant to have to start wearing it at night. I use it for exertion and my sats are normal when sitting. I never wake up like I can't breathe. Just afraid I am going to get to much oxygen. Can you help me understand this nighttime 02 and if it helped you..