Low blood sugar can keep you awake for hours.
The best time to carb up is post workout.
If you are tossing and turning, eat a couple of pieces of sugar candy. That's about 22 grams of carbs for Orange Slices, and within about 10 minutes, you should be feeling a lot better.
Lots of folks mistake low blood sugar / under-eating for sleeplessness / migraines and tension headaches.
This is especially true in folks that don't eat early in the day.
If you're training late, it's important to eat late, as well.
If it's not low blood sugar (a sure-fire way is to test it with a glucose meter, like we do), then, likely, you're just getting "wired."
3 shots of vodka and some Zanax will fix that. LOL. Just kidding.