Also consider that your situation has nothing to do with the selenium, or iodine. If adrenal fatigue, one easily overload the system. I did.
I have overdone most supplements; this was for me the greatest teacher. I learned to quit everything for a week or two, then slowly add one supplement every 3-4 days.
This way I found out that vit B`s was the worst for my insomnia; it actually caused it.
It kept me awake even if I was dead tired. Caused a heavy pulse, palpitations, jitteryness, thought rush.
It is a rare reaction, but I had it. Had to quit vit B for a long time. It has to do with the adrenal fatigue, but I dont know why. Just the experience-knowledge. Now when my adrenals work reasonably well, I tolerate vit B without problems.
Salt, and lately potassium; is great for the adrenals.