Jade Geary and Brittany Hickey have published "When Does Burnout Begin? the Relationship between Graduate School Employment and Burnout Amongst Librarians" in In the Library with the Lead Pipe.
Here's an excerpt:
The purpose of this study was to identify the percentage of LIS workers (current and former) and students who have experienced burnout. Additionally, this study focused on the correlation between those who work while obtaining their LIS degree and whether or not they later experience burnout. These objectives aim to answer the question: what percentage of future librarians are more susceptible to burnout once they enter the profession because they are currently working while enrolled in classes?