When my daughter gets fevers we stress dose and wake her in the night.  I would NOT just let him sleep!!  Fevers can kill those with CAH.  When my daughter has a high fever for over 24 hours she usually vomits from it.  That is our signal to give the injection.  She doesn’t have a stomach bug she is going into crisis.  She responds so fast and the fever is gone sooo quickly I always end up wondering why we didn’t give the injection sooner.  In any case, all those with CAH are different and you must get to know how your child responds to illness and stress dosing.  It sounds like your sone is given cortef twice a day.  If this is correct, in times of illness I would take the total daily dose and triple it.  Then I would divide by 4 and give tha amount every 6 hours.  Cortef is short acting and his body willuse it all up before 12 hours are up.  Talk to you DR. about any changes of course, but waiting all night with a high fever can be waiting too long.  Goo luck.  Julia