I'm 40 years old and have an under active thyroid for the last 4 years. I started on a low dose of thyroxin and over the last few years has it been increased just lately from 125 mg to 175 mg. My question is I was feeling awful with lots of symptoms including extreme fatigue. Once my dose increased almost overnight I began to feel more human again, my sleeping in the day just stopped and I found myself with lots of energy all day witch was fantastic. Unfortunately this only lasted for approx 17 days ( as I kept a diary) since then I have began to go down hill again feeling like I used to feel but not quite as bad as before. Have had to start sleeping again also along with some of my other symptoms creeping back. Has anyone experienced this before can it be common to see and improvement then regress again? I am due to go back for bloods at the end of the month.