A few days ago I woke up feeling really groggy, as if I hadn't slept. As I lay there, I thought 'Oh, is this what they mean by "unrefreshing sleep?"'. I tried to think of what I had eaten or done that would have caused this. Eventually it occurred to me to check my diary. Yup, 21 days since my last T2 (thyroid hormone) boost. I took some T2, and felt at least back to my usual level of symptoms the next day. I don't know if it will work for anyone else, but I know how it feels to be desperate for relief, and 'willing to try anything that isn't obviously dangerous but which _might_ help'. I hate to think of others waking up feeling how I did a few mornings ago when maybe they could avoid that. What works for me is taking T2 (3-5 diiodothyronine) when I feel that drastic rise in symptom severity, which for me occurs every 21 days. It's an abrupt increase in symptoms, so something in my cells is switching states rather than just gradually running out of something. One dose (100 mcg) is enough, and half that seems to work too. Taking it for longer doesn't provide greater improvement, and when I took it for several days and then stopped, I suffered greater symptoms again while my thyroid gland readjusted. If I'm low on dietary iodine intake, a drop of tincture of iodine seems to boost my thyroid's production of T2 enough to accomplish the same thing. Sodium or potassium iodide might be a better alternative to tincture of iodine, but the latter is what I have on hand for minor injuries. I first discovered the "T2 effect" when my disorder seemed to be just a type IV food sensitivity. I took a multivitamin tablet and felt 'cured' the next day, with abundant energy. After testing separate vitamins (with no benefit) and then minerals, I found the active ingredient was iodine. After the first few times, I no longer felt the wonderful improvement, and stopped taking it. Much later, after wondering why iodine helped and T3 and T4 supplements had no effect, I asked myself the question: 'Does the body do anything else with iodine?' The answer was that it also made T2, which was first considered inactive, and later found to be critical for RNA transcription among other things. I found some T2 online, gave it a try, and the first test made me feel temporarily 'cured' again. As with the original iodine effect, it stopped giving the huge effect, but I found that every three weeks or so I'd abruptly feel lousier and that taking T2 would 'reset' something. It was only this last time that I connected it with 'unrefreshing sleep', since that's a concept I only learned about probably since the previous event. If anyone gives T2--or iodine--a try and finds a benefit, please post for the benefit of others. Conversely, if you have taken iodine supplements (maybe in multivitamin/mineral tablets) and didn't notice any reduction in CFS symptoms, that would be useful information too. I'm not sure if the effect works if you continually take iodine or T4 or T3 or T2; I don't think I took iodine or T2 supplements for more than a week or so. I should add that the only T2 supplement I've found is San Corporation's T2 Xtreme. The first bottle I bought was the previous version with just 3-5 diiodothyronine. The new version also has the 3-3 isomer. The new version doesn't seem to work any differently for me. It's marketed as a weight loss product. BTW, taking once capsule every three weeks hasn't slimmed me at all.