The combination of prolonged immobility, especially when seated for long periods, along with dehydration which can also occur on long journeys, can cause a number of circulatory problems, including Deep Vein Thrombosis. Wearing properly fitted graduated compression hosiery helps force blood up through the lower legs cutting down the risk of blood clotting. This graduated compression hosiery can help reduce the effects of air travel as well as reventing swollen ankles and tired, aching legs.