I'm a 35 yr old non smoker & non drinker. My pcp sent me for a sleep study & called me today to tell me that I don't have sleep apnea but my oxygen levels dropped dangerously low & wants a pulmonary specialist to see me. He said it could be stress & anxiety or heart/lung disease? My other symptoms are headache, dizziness, & I'm always tired. Does anyone have any input on this - cause I'm freaking out.