ASHDOWN, Ark.—As an anti-aircraft gunner on a Navy attack transport ship in the Pacific during World War II, Otis Bell was on perpetual alert status.

“I learned to sleep standing up,” the Little River County resident said. “There was no dragging around—you had to be in place in a matter of seconds whenever general quarters sounded.”

Bell, like many others exposed to battlefield carnage, would find sleep elusive for years after his war experience.

“I came back home a nervous wreck,” said Bell, 83.

“I would get up in the middle of the night becau...