I hear from travelers who notice puffy legs after a long flight. Some worry about a blood clot, but this almost never causes both legs to swell.
Your heart has no trouble pushing blood to the far end of your body but plays no role afterwards. Blood returns to the heart slowly, squeezed along by surrounding muscles. If you don’t move, it returns even more slowly. In the absence of movement, gravity induces blood to settle in the legs where plasma leaks through the distended veins into surrounding tissue. You can make the diagnosis if pressing a finger makes a visible dent. Veins grow leakier with age, but I see plenty of guests in the prime of life. The swelling should diminish after you begin moving or eliminate the effect of gravity. A night in bed usually helps.
Textbooks list dozens of serious causes “peripheral edema.” I can’t recall a hotel guest who had one, but it’s possible that a traveler with swollen legs may learn that he has heart, kidney, or liver disease and remember that I downplayed its seriousness.
So, my legal advisor insists I warn you not to feel reassured by what I’ve written. It’s just my opinion; you might be dangerously ill. Consult your family physician. Go to an urgent care clinic. Call the hotel doctor.