I ve had a number of intermittent episodes since last August where I get a combination of minor nausea / light headed feeling and sensation of being short of oxygen/passing out (though that has never happened). This generally happens early morning while in the sitting position and worse it pretty much only happens when I m driving. This lasts for a few seconds, goes away and may return in five to ten minutes. Once on the job or moving (upright position) it s as if there was nothing wrong. I am a smoker, cutting back, intend to quit, I cough up small amounts of clear to milky flem on occasion. the only other thing I believe may be related is upper back problems I ve been seeing a chiropractor about (pinched nerves that may affect the respiratory system?). Other than I should quit smoking for all other good reasons, any Idea what may be causing this? Additional info,55 year old male relatively good health, Hike Snow ski, physically active construction contractor.