Any employee who experiences burnout and fatigue will not be a productive employee. What about nurses who are in-charge of taking care of patients? How would they be able to take care of other people when they are not taken care of themselves?
Here's a survey on Employee Engagement in Nursing saying that nurses do love their work but are battling fatigue. Check out this article Reduce Nurse Burnout by Treating Them as well as We Treat Patients.