Pull in the wagon

"No matter how busy and varied your schedule is during the day, you absolutely need some stress-free time during the evening to pull in the wagons and create a sense of peace, tranquility and security."

What is the origin of this expression and its meaning?

Well, since nobody more authoritative has replied, I would say that it's a reference to the wagon trains of pioneers that crossed 19th-century America. Every evening at the end of the day's journey they would pull in the wagons, to camp for the night and rest. (VSD)