While beneficial for their employees and the organization, it's an especially draining activity for managers," he said. "In fact, we found it had negative effects for managers that spilled over to the next workday."As part of the study, researchers surveyed 82 bosses twice a day for a few weeks. Managers who reported mental fatigue from situations involving procedural fairness were less cooperative and less socially engaging with other workers the next day."Managers who are mentally fatigued are more prone to making mistakes, and it is more difficult for them to control deviant or counterproductive impulses," Johnson said.reenex