Perhaps this will be interest of you if either you or a close relative suffer from bipolar disorder (Formerly called manic depression).
First of all; I have not been diagnosed as hypothyroid, but display all the symptoms. However, I have been diagnosed as bipolar.
There are several studies that indicate a link between bipolar and thyroid related illness'.
Against recommendations, but desperate for relief of my symptoms: cold intolerance, dry skin/hair, drained of energy and insomnia, I recently began a course of Levothyroxine 50mg. It certainly helped with the incessant coldness, but after a couple of days, my mind began racing and I was writing and writing (most of it not making any sense) and realised I was going into a hypomanic state whereby all sensations were heightened and I was losing touch with reality. I'm not suggesting the medication can cause this, but may trigger it in people who already suffer from bipolar. In fact, my body reacts in a very similar way to SSRI anti-depressants.
Here is the best website I have found on this subject: psycheducation.org/treatmen... (written very concisely, easy to digest and backed up by various studies and empirical data) written by an American psychiatrist, Dr Phelps.