Going back to the Op original post... odd that it is - the whole point backpacking IS a vacation - in the woods... no need for alcohol,pills,drugs...etc, That doesn't make me old, I have done my fair share - but keep in mind what a doctor puts up with when you are not sick... he pushes pills to make ya go away till the next time... when was the last time your doc recommended a vacation in the woods?? Well sorry to say Motel 6 and your doctor isnt a travel agent... so off to the pharmacy for you.
IF you are seriously having issues with falling a sleep - Get over it! there isn't a quick fix! But the most important issue is not dwelling on the stress. It takes folk at least three days to five to get in the groove of Backpacking.. On my bad nights I focus on a "driving" or riding a horse across the field memory and I play it over and over again as I attempt to sleep - I never finish it - I'm out!