One in four office workers complains of "chronic boredom", turning to coffee and chocolate to lighten up their day.
People are also more likely to have an alcoholic drink at the end of a boring day at work, a study of office-based employees showed.
Four out of five of those surveyed by occupational psychologist Sandi Mann said boredom caused them to lose concentration, and half believed it led to mistakes.
Around half said being bored at work might lead them to look for a new job.
Dr Mann, of the University of Central Lancashire, said: "My analysis suggests that the most significant cause of office boredom is an undemanding workload, so managers should look at ways of reducing sources of workplace boredom and encourage better ways of coping.
"This could involve enrichment programmes such as job rotation, multi-skilling and empowerment. Encouraging healthier ways of coping with boredom could include education or providing healthy snacks and drinks in canteens."
The study, among more than 100 office workers, also found that some people are more prone to boredom. The research will be presented to the British Psychological Society's annual occupational psychology conference in Chester.