Some years ago, I suffered from the symptoms of chronic fatigue syndrome following a bout of pericarditis. After the usual extensive tests found nothing wrong and people started to suggest that there was nothing wrong I forced myself to return to work (no medical issues for me).
I then had to attend a business meeting in Boston Ma and thought that I could just about cope as, apart form the actual meeting, the trip mostly involved sleeping on aeroplanes or in hotels.
I arrived in Boston late on a hot June evening to find that I had no luggage (gone to Paris) and no hotel (should have been booked for me). All hotels near the airport were full so I went on a little adventure to find a motel and then to organise getting my luggage. Something in me tends to enjoy this sort of challenge and I soon forgot how ill I felt. Strangely I never felt ill again and I have often wondered if adrenalin has any effect on ME.
Apparently there is a thing called "adrenalin loop" which suggests that there is a strong connection between ME and the body response to adrenalin, which can be too high or too low. I don't really understand it but have found some explanation here:
http://www.simpsonandfawdry.com/page2.htm
I often jokingly suggest to occasional ME sufferers I meet that a really good fright might cure them. I even offer to take them flying but, as yet, no-one has taken up the offer.