Has anyone seen any research suggesting lower oxygen saturation for CFS patients? Typically what levels are seen during the acute phase of the post exercise malaise? I wish I had thought to buy this before, but I just picked up a 24x7 data logger oximeter. You can wear it while you sleep or exercise, and pick up your oxygen levels and graph on the computer. Very nifty little device. I would love to have been wearing this a few months ago when my PEM symptoms were extreme.