I’m glad you got ONE good night’s sleep at least, that’s promising — at least you know that every once in a while, you’re capable of sleeping through the night.
The problem with “our” kind of insomnia (while hyperthyroid) is that it is CHEMICAL. It isn’t just that our mind is racing (even though that’s true), it’s that the gas pedal on our body is pushed all the way to the floor. That means everything that usually works for other people is not likely to work as well for us. It may help, don’t get me wrong, but it may not, and then we tend to feel even more frustrated.
We did have someone speak on this topic at a conference, and I remember it was specifically tailored to “our” kind of insomnia. There are a couple of things that may help — first, don’t attach too much significance to the actual “snore-fest” version of sleeping. Laying down and being still gives our body nearly as much benefit as sleeping. Our problem is that we get frustrated and anxious because we’re not falling off to sleep, so we lose any benefit we might otherwise get from just being still and resting in the dark.
Next, STOP looking at the clock. One look at the clock starts the whole internal conversation — “look at what time it is, S***! If I can fall asleep right this second I’ll only get xx hours and xx minutes worth of sleep before I have to get up, and that’s not enough, and now I’m worried about what I have to do tomorrow,” etc. etc. So keeping that information out of your grasp is better for your state of mind. Do whatever you need to — cover it, hide it, turn it to the wall, but keep those numbers out of your field of vision.
Also, do not look at anything with a bright screen (smartphone, tablet, laptop, TV) — bright lights tell your body that it’s daylight and time to get up, so you’re telling your brain to activate, then trying to lay back down.
The soothing sounds is a really good idea, and if you can get that to “loop,” even better, that way you won’t have to put any brain power into that either (“is it off? did it end? should I start it again? how long ago did it go off? have I been asleep?”).
Finally, if you’re really, truly awake, feeling like you’d just rather get out of bed, then do that, but choose something quiet you can do in dim lighting, like reading an actual book, or the paper, maybe make a cup of tea. Something that’s rather passive, so you can keep yourself in a semi-relaxed state while you do it. Give yourself 10-15 minutes, then head back to the bed and try again.
I know it sucks, I remember it all too well. I hope you find your best way to get rest while you heal and recover!