Many of the infections associated with Lyme cause oxygen deprivation in the brain to varying degrees. Sadness, irritability, and confusion can all be symptoms of relative oxygen starvation.  I never used to react like this, but the last 4 Winters I've had Lyme, skiing at our place in CO can exacerbate my cognitive and emotional symptoms. The link between mountains and airplanes would seem to be oxygen levels.

Obviously airplane cabins are pressured, but since our brains are already getting less oxygen than that of a healthy person, I think we are particularly sensitive to even slight decreases in ambient oxygen levels. I can see how even after a pretty short flight  the oxygen levels would be slightly below what you'd get at or near sealevel.

Early on when I got ill, I did not know I had Lyme. I had to make a 2.5 hr flight home to visit my folks. The day after the plane ride, I woke up to gaining 27 lbs (yes you read that right) of fluid! I looked like freakin Bib the Michilen (sp) Man!

I could not move my ankles, toes, arms, wrists...you get it. I was in agony and could barely move.

Went to the ER and 1st thing they said was Congestive Heart Failure. Yeah right. Wanted to admit and run all kinds of tests...not happening.

I took OTC fluid pills and in 3 days was back to normal, although my legs ached for days after.

The flight home was not near as bad, as I took fluid pills just in case. I have not flown again!

Prior to this, I used to fly all the time. Long overseas trips as my job required it and I never had a problem.