From what I understand and have read, there are several things that can give a person insomnia. Even if you have RLS, that does not mean that the RLS is the only thing keeping you awake (usually in the form of too much glutamate.) There is too much histamine, cortisol spikes, etc. etc.
Here is something simple and which won't cost anything beyond your usual grocery expenditure. This is a bed time snack and if needed a middle of the night snack upon waking up. But not just any old snack. It's (healthy!) carbs. Don't scoff, as I did what I first read about this! There is a science behind this, and I will tell you it has been working well for me.
Low carb is something that has been causing many people to have insomnia. You can read about this here (or look it up as well.) psychologytoday.com chasing away insomnia with a bowl of oatmeal. You can also read about it at livestrong.com I can't sleep on a low carb diet
Another thing that causes insomnia is Intermittent Fasting (sorry) in people who already have sleeping problems, such as adrenal stress, dysregulation, etc. Chris Kresser has an article on Intermittent fasting, cortisol and blood sugar. Those cortisol spikes in the middle of the night wake you up.
Julia Ross also mentions how needing something to eat before bed and possibly in the middle of the night might be all one needs to cure the insomnia. She mentions that the blood sugar drops and this turns on the cortisol (presumable to make you get up and get something to eat.) The cortisol spike wakes you up.
If one is squeamish about adding too much carbohydrate to their diet, then consider changing when you eat carbs. For instance, rather then having them early in the day, strategically eat them later in the day/before bed. Alan Christensen (sp?) of the Adrenal Reset Diet book, recommends this.
And of course, It is not sugary foods, or even fruit, but healthy whole grain carbs, or for those who are staying away from grains or beans, it is potatoes, sweet potatoes, butternut squash, carrots. But I am not going to get too carried away with what. It is the science and chemistry behind it all. Check it out and give it a try.
I tried this a few months ago and it worked, then I didn't need it as I was sleeping well. Recently, I went thru a bought of waking in the night again, forgot about this, suffered for 3 nights, until I remembered - get something to eat! So I did and tho I wake up, a half a slice of whole grain bread puts me to sleep for the rest of the night. Don't toss and turn for 2 hours, as I did. Get up right away! Try this!