The study, published in the Journal of Clinical Nursing, says healthcare staff use humor to not only reduce tension and express frustration, but to connect with patients and make them feel cared for as individuals and reduce their embarrassment.

Study co-author Dr Ruth Dean of the University of Manitoba and colleagues spent spent nearly 300 hours observing and carrying out interviews in an intensive care unit and a palliative care unit.

For example, a patient reported she felt less distressed by an episode of incontinence when the nurse said matter-of-factly "what goes in must come out."

Most staff say humor helps them cope although a nurse observed: "If I'm joking with you, I'm interacting with you. We're talking but I don't ask you what's bugging you ... I'm not really finding out why you're upset." Overall however, humor helped healthcare professionals to connect not only with patients but with each other and shared laughter nurtured a sense of community.

"Our research suggests that nurses and other healthcare professionals don't need to suppress humor," Dean said in a statement.