I have hypothyroidism, but in the past, (much younger) I had a hyperthyroid.  It wasn’t too high, but enough to give me problems.  I was "on the border".  I took Propythyrocil (sp?) for a short spell and everything was in order.  Now, over a 4 year span I would say I have "spells" where my thyroid falls right below the levels considered normal.  Again, borderline.  BUT, when this happens I hit a wall about 2 in the afternoon where I cannot function.  It is all I can do to keep my eyes open, even when driving.  I have to go home, put my kids on the bed with me and crash.  I am a hoot owl, never EVER take naps, never needed them so this is highly out of the norm for me.  My heart beats irregularly and it exhausts me.  I feel almost as if I am drunk, I stagger, become lethargic, am intolerant to cold and have no other option than to nap midday in order to get through until night time.  There are some nights that I lay awake in bed, my heart feeling as if it is going to jump out of my throat and I think that I am going to die because my heart is going to give out in the middle of the night.  The only doctor that has listened to me since I have been in CA is my OBGYN.  He did labs and found that my cortisol, test., and estrogen levels were below the normal range.  My thyroid was under the normal range and he put me on medication again.  Within a week I was able to get through the day without those "drunken" spells.  I told him about carriers and he has done another work up on me, testing as if I had CAH.  He is a unique OBGYN, specializes and only takes on women who have complicated OBGYN historys.  Very interesting about the diet, and he put me on one similar to what you mentioned Ann-Marie.  I have followed it and am feeling much better.