Does anyone else get fevers on long flights? I've flown 3 RT international flights in the last year, and felt feverish on all of them. A low fever, but keeps me from sleeping unless I take tylenol. I can't find anything on google (possibly bad air quality or mild altitude sickness?) and am not sure if my body is just insane. This never happens on domestic or shorter flights. The fever starts a few hours into the flight, and ends 2 hours after the flight (just long enough to make customs miserable).