Marissa Mayer on burnout:
"Burnout is about resentment," she said. "It's about knowing what matters to you so much that if you don't get it that you're resentful."
"Burnout is about resentment," she said. "It's about knowing what matters to you so much that if you don't get it that you're resentful."
(ie people reporting burnout are usually temporarily sterile, people who are "stressed but happy" are usually not sterile)
This is why burnout correlates so strongly with being overworked. Your body is rightly concluding it can't reproduce in your current situation, and gives you a strong prod toward fixing the problem.
Apparently Marissa's "resentful meter" correlates strongly with her body's "I can't reproduce in this situation meter". I don't think this is true for most people.
Both have very good data in the top 10 results. If you're looking for a pop sci writeup, I'm not sure if there's a good source.