India, April 12 -- I'm a travel writer, and my rose was a recent trip: six glorious days sipping rose and playing with free-range pigs at Spier Wine Farm in South Africa. The thorn? I had a swollen ankle when I arrived.

Admittedly, it was my fault, and it was the result of an experiment: What would happen if I only wore one knee-high compression sock on the 15-hour flight from Newark to Cape Town? On my other foot, I wore a regular ankle sock to see just how effective compression socks can be for circulation while in the air. Surely, after 10 years of flying across the Atlantic monthly for my career, my body has acclimated to spending hours at high altitudes-right?

Spoiler alert: it hasn't. As it turns out, you can have a million-miler...