Rudeness in workplaces can spread like a virus - particularly if the boss is in an irritable mood, a study suggests.
Being on the receiving end of even subtle forms of aggression at work, such as dirty looks, gruff words or simply ignoring colleagues, can spread "like a disease".
In turn, uncivil behaviour from supervisors and colleagues can lead to bullying, and may cause sickness and ill health in those on the receiving end, scientists claim.
Researchers say that even low-level petty behaviour, such as leaving someone off an invitation to a communal event or spreading rumours, can start the cycle off. They found witnessing a supervisor being uncivil to another worker was often enough to cause people to be rude to those around them.
Dr Eva Torkelson, a psychologist at Lund University in Sweden, said the most common cause of people acting rudely at work was imitating the behaviour of others.