*1.1. Theoretical and Empirical Background Linking Workplace Bullying to Employee Well-Being*

Workplace bullying is generally defined as situations where an employee is exposed to negative actions on the part of co-workers, supervisors or subordinates repeatedly and over a period of time [25]. It is different from workplace violence [26] or occupational stalking [27] in its nature of repetition, persistency, hostile intentionality of negative acts, and power imbalance. Some forms of workplace bullying behaviors include wrong or unjust judgement about a bullied employee's work performance, criticizing one's personal life, restricting expression of personal opinion, assigning meaningless tasks, and backbiting. Such negative actions are unwanted and resented by the victim employees and may cause humiliation and distress in victims and also potentially in observers [28].

Previous research has observed the negative consequences of workplace bullying on employees' health and well-being, including deterioration of psychological well-being, complaints about physical and somatic symptoms, and poor quality of life [29–32]. Both the victims of bullying and the observers report more general stress and mental stress than those without bullying experiences [33]. There may also be a long-term health consequences of workplace bullying. A 3-wave follow-up study from Danish employees in a period of four years has shown that negative health problems caused by workplace bullying (e.g., poor self-rated health, sick-leave, depressive disorders, and sleep problems) last over several years even after bullying was discontinued [34].
