Hi All, first time I've posted on here but have changed from T4 levo to nature throid and after slowly increasing I'm at the right dose of 175 according to my last blood test, so I'm on the right dose for me. However, every evening I have this crushing tiredness (I'm up 5.30 for work and work full-time) but I've gone from a person who could never catnap unless I was ill, to one that cannot stop. I've recently had blood test and my ferritin and folate b12 etc are all in range. My TSH was just under .05. I did feel far more awake on T4 so I'm disappointed with nature throid at the moment. Does anyone else share this experience or know what else could be causing the tiredness?