Parents with the ped endo may decide to dose this way for side effects from the Cortef meds.  Some people have no problems with a 2 or 3 times per day dosing schedule.  Others have side effects which can be different for each individual and can include:  slow growth (weight or height), moon face, moodiness, weight gain etc..  The simple way to put it is this.  The goal of medicating someone with CAH is to suppress the hormones with the least amount of hydrocortisone as possible.   Most doctors prescribe the easiest method of giving the meds due to worrying that the meds won’t be given.  This means 2 or 3 times per day dosing schedule.   Each of the doses is rather large and expected to last 8 to 12 hours when given.  The Cortef is short lasting and only lasts at most 6 hours.  Often people metabolize rather quickly and absorb even faster than this.  The theory is that if the meds are given in smaller doses and spread out throughout the day in the same percentages (largest doeses at 3am and 7am as "normal" bodies naturally secret the most cortisol)  that control can be achieved with with less meds and without rises in hormones in between doses that can cause problems.  The meds can work more efficiently.  We have seen this happen.  Our daughter was originally on 2 times per day (as a baby on the same daily total as my daughter is now at 5 1/2 years.)  Her old endo (got rid of him for many reasons) put her on a huge dose to hope in vain that it would last until the next dose 12 hours away.  She was so oversuppressed.  Huge, red cheeks, wouldn’t sleep, was cranky and wouldn’t grow.  When we went to 3 times per day we lowered her dose.  When we went to 4 times per day her dose was lowered again and she began to grow, finally!  Now she is on 5 times per day.  It really isn’t all that hard.  One with each meal, one before we go to bed and the 3am dose.  We have the "markers" to help us remember.  Sometimes out and about we forget for an hour and then give it.  No worries though.  She is doing fabulous.  Her weight and height are right on as is her bone age.  She is happy, her cheeks aren’t red and are normal size now.  I am a firm believer that if your child is having side effects that this works!  Good luck.  By the way, I had to really convince our endo to do this.  I brought in 21 pages of information and graphs to show why I wanted to do this.  Now she is a firm believer in it and thinks this way of dosing is far superior to 3 times per day but unfortunately she finds that compliance would be an issue for many parents.  Julia