When former U.S. Army Special Forces sergeant Alan Shebaro returned to Texas in 2010, he knew others wouldn’t understand. He’d finished serving three rotations in Iraq but knew plenty of others who had it worse. For starters, Shebaro still had all his limbs. He’d accomplished the goals he set for his military career, almost to a tee: a drill sergeant in peacetime and a Green Beret in wartime.So how come he couldn’t get to sleep without a six-pack of beer, three Benadryl, two Ambien, about eight jumbo melatonins, and any Percocet he could find? How come when he rose in the morning, he needed a triple dose of Adderall to get through the day? How come he eventually found himself ready to blow a head…