Only research I can give you is 'in the field'...when a boss remarked on the problems of another flight department, where the pilots were held in indentured servitude with contracts and such. He thought it was nuts to make pilots unhappy, then give them planes and people to fly around.
I know from personal experience that many pilots are barely capable of doing more then getting the plane from point a to b...add in stress, money problems, apathetic attitudes, lack of ethics, morality, etc, and it's a deadly combination of a pilot that is now just 'past it' when dealing with an in flight problem.
Sim instructors load up pilots all the time to failure...pilots bringing in all their problems to the sim, just means they hit the wall sooner.