I was in the hospital for atrial fib for two days last week. I am 80. My oxygen levels stayed at a steady 97-98 percent while confined to the hospital. My lungs are very clear. I work out three days a week at a fitness center and include an additional one or two rounds of golf. During a nighttime sleep oximetry test while at home this week, my oxygen level dropped to 78 percent for 20 minutes. Should I be overly concerned? I suspect sleep apnea but cannot see myself using a CPAC while sleeping. Your comments.