This is my area..!
I've had insomnia for years. It got worse when I went vegetarian, and got worse again when I went low carb. I've researched it to death, have asked several big boffs about it, and never found a satisfactory answer. I have several hypothesis about it.
Are you fat adapted? Hows your fat intake?
Basically, when the average, sugar burning person sleeps, they use up glycerin stores. When these get depleted (which they do easily - particularly if you're eating low carb), the body cannot rest, because it starts looking for fuel. The result is waking fitfully throughout the night. Some people wake up hungry, others just wake up with a racing mind.
If you've changed to primal, but haven't upped your saturated fats considerably, you're still relying primarily on sugars as your source of fuel. Unless you're eating really heavy carbs at night, these get depleted quickly. Your body goes into a state of stress, because it's searching for fuel, and it makes you wake, feeling stressed out, or hungry.
If you're fat adapted, it doesn't matter if your glycerin stores are low, because your body has a constant source of fuel to keep it in a state of rest.
Another thing is hypoglecmic insomnia, which is when your blood sugar drops too low and again, you wake up looking for food. Or your liver can respond by dumping glycerin back into your blood stream, and the burst of energy wakes you.
I'm in the process of adapting to fat burning, and I'm still waking up for an hour each night- but not feeling hungry anymore.
I know other things it could be too - tell me more of your symptoms and I'll see what I can share.