Having a flexible work schedule isn’t always a good thing. Employees who have full or partial control of when they arrive, leave and complete their work tend to blur the borders between work and other parts of their lives, a new study shows. While workers with no schedule control tend to report more conflicts between job and family demands, those who have a say in their schedule are hardly free of stress, according to Scott Schieman, lead author of the study. The workers with flexibility tend to blend their work life with their family life by performing job duties at home. This merging can cause physical and mental stress and conflicts with their co-workers, spouses and children.