Doping

"A low level of cortisol could be indicative of corticoid use or of fatigue."

But their rules are that the rider should be rested. Of course, he's not going to rest if he's not tired and is in fact feeling great because he's using cortisone..

There are very few rules to go by on the MPCC site,
the case is clearly stated.
So it's a very clear concern, and well known to this selfregulated industry.
http://www.mpcc.fr/index.php/fr/mpcc
Bernaudeau is still smiling at the bottom of the page.

I did a quick check on daily variations of cortisol level on a health forum:
the samples should be taken from 7 to 9am,
it was stated as well that low cortisol levels can lead to sudden deaths.