I've tried antihistamines, the basis of all OTC sleep aids. I go to sleep but then wake up several hours later with my heart pounding, almost like a panic attack. Then I don't go back to sleep at all.

With an "old lady bladder," I'm up 2-3 times during the night anyway. If I'm not feeling sleepy, I may stay up for a while and watch the stars--so spectacular when away from the lights of civilization!

If I have a short night, I just push through the next day, knowing that I'll sleep well the following night. I've also been known to take an hour's nap during the day. There's nothing that will produce insomnia more easily than lying awake worrying about not getting enough sleep!
May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view--E. Abbey