AA717driver raises one key issue.
However, not only is stress now much more severe than as little as twenty years ago, but the whole package of flight time limitations, rest periods, disturbance of sleep patterns, lack of provision of crew food, suitability of overnight accomodation, treatment of staff, career dislocation, type conversion workload, attitude of co-workers, forcible geographic relocation or commuting due forcible relocation, professional liability, danger, frequent but unrealistic competency checks, frequent medical checks etc etc all adds up against even the most resilient of human beings.
Some of the above are unavoidable, but a great many are not, provided that Aviation Authorities recognise the fact and take action to legislate in favour of professional pilots.
BTW, closer to topic, alchohol levels above regulation limits is TOTALLY unacceptable. Becoming teetotal is the easiest solution, and should become mandatory for all pilots, commercial or not, IMHO !