The thing that I've found helps me get to sleep is simple exhaustion.

My typical camping trip in the GSMNP, but I live about 6 hours away. So to save money on a hotel room, I simply wake up about 3:00am. By the time in include a shower, getting out the door, stop for breakfast, etc... I get to the trailhead around 10-11am GSMNP time. Hike 8 to 12 miles (usually including a major up-hill), setup camp, make/eat dinner, and I'm pretty much worn out by the time the sun sets. From there, I simply go on 'sun time' til I return home.