Great clarifications above on the different tests, not for the first time do i wish i had found this forum a year ago! Had to learn all that in bits and pieces.
I did the 4x / day spit test (three separate times over the past 18 mnths), and ACTH, and cortisol blood tests at three diff times of day (different days).
My ACTH was fine, and the side effect was that for an hour I felt "normal" eg not sick with CFS/ME. That in fact is what I keep going back to when I worry if I could ever feel better again. It is what I percieve folks are saying for instance on the antiviral threads about their recovery, makes me think it's possible. But I digress...
My cortisol curve was the same in all three tests, which were spaces out about three months apart: cortisol peaks early, goes quickly to low normal midday, and crashes around 3-4 pm to below normal, which is congruent to both my energy levels and emotional outlook/attitude. Blood tests confirmed a marked, significant drop from midday to 7pm. My MD raised his eyebrows and wanted me to start supplementing cortisol. Not ready to go there at this pont.