Support/compression hosiery (stockings, pantyhose, tights) are a trick of the trade for flight attendants. They help prevent the pooling of blood in the lower legs and feet that happens in a pressurised cabin on flights. A particular risk is deep-vein thrombosis, a condition in which a blood clot forms in the legs and then breaks off and blocks blood flow in the lungs.

Studies in healthy people have shown that wearing compression hosiery minimizes the risk of developing deep-vein thrombosis when taking long flights, so yeah guys, support hosiery might be a good idea for you, too, according to doctors. But get the kind of compression hosiery made specifically for this purpose and available at department stores and pharmacies (like Guardian, Watson). You can also purchase support hosiery online, like from Solidea. Avoid regular socks if they have very tight elastic bands at the top, and don't sit for long periods with your legs crossed, because this can cramp circulation in the veins.

Personally, I find those knee-high support hosiery to be not very effective as the compression only goes up to the knee/calf. Support pantyhose (there are male versions too, if you are not comfortable in wearing female versions) offers graduated compression all the way up the entire leg. You don't need to fly in order to wear support hosiery. If you stand or sit for hours throughout the day, you can wear them. Your legs will feed great due to the better circulation in the legs at the end of the day. Support hosiery also prevents the formation of vericose veins.

So, for the sake of better leg health, wear support hosiery whenever possible, even with your bermudas/capri pants.