At Stradishall for the Advanced Nav training course, our Dep Course Cdr had just arrived from Canberras. After the longish overseas trip to Gib we did at the end of the Varsity phase, he mentioned quietly to me that night that he had been physically ill that morning at the prospect of some 7 hours flying without an ejector seat - something he'd never done before.
And by chance, the British Journal for Military History has just published a WW1 edition that can be downloaded free. It contains an article on early medical perspectives on the "Nervous Flyer":
The Nervous Flyer: Nerves, Flying and the First World War | Shaw Cobden | British Journal for Military History