Anytime I hear people talk of mental state (among a few others) having been the first thing that comes to mind is the B vits. They are crucial for proper nerve function and I recently read that B deficiencies are higher in your part of the world. Any nutritional supplement plan can take some time to kick in, generally the older we are the longer it takes.
If your found your mental stat improved when you started Iodine and then deteriorated I would consider the problem larger than just thyroid related. As Gina mentioned, adrenals can cause a lot of sleep issues, lethargy etc.
Ive had great results with high dose B12, b9 and niacin in the proper forms....along with a good B complex.