My husband had a heart attack 7 years ago and then followed doctors orders faithfully including taking the meds. Didn't make any lifestyle changes since the doc said just keep eating your regular diet "in moderation." So he ate huge steaks, barbecue, chinese takeout, pizza, and cheesecake "in moderation" and didn't worry about it, cuz hey he was taking his meds and following doctors orders.
Of course, a few years later he had to have an "emergency" triple bypass which was very fortunate because it FINALLY scared him enough to WANT to change. Now he doesn't take meds, he exercises twice a day, and -miracle of miracles- he eats whatever I tell him to, including iodine, bowel cleansers, cayenne, and weird things I grow in the cupboard like sprouts, kefir, and kombucha. He's now in the best shape of his life, is stronger and healthier than anyone I know and his life has improved dramatically.
My point in telling you all this is - until HE is motivated to change his lifestyle you're pretty much wasting your time looking up stuff for him. Just taking some Iodine isn't going to do much one way or the other. Yeah, it's probably safe. My husband has been taking 100mg for months and hasn't even had any detox. On the other hand it's only a mineral, not an instant miracle drug or sleep aid, and it's not going to take the place of cleansing, eating healthy, exercising and kicking the drugs.
For sleeping problems - he should be out walking in the sunshine at least once a day. Strong sunlight helps regulate melatonin production so he should be outside at least half an hour a day. What HE (not you) should be looking up is healthy exercise and sunshine to help with sleeping problems AND researching the drugs that are being foisted on him. If he isn't willing to put out the effort to look up any of these things, you're wasting time that could be better spent looking up stuff for the one person you CAN change. YOU!