Having a sense of humor has health benefits but the actual act of laughing can reduce lung function, at least in the short term, U.S. researchers suggest. The researchers evaluated humor and laughter in patients with chronic obstructive pulmonary disease. Participants who exhibited a greater sense of humor were more likely than others to report fewer symptoms of depression and anxiety, and better quality of life -- and tended to report that they had experienced fewer respiratory illnesses in the month before the study. However, the study published in the journal Heart & Lung, finds patients who watched a 30-minute comedy video and laughed during the viewing had lower pulmonary function afterward than did patients who watched a home-repair video that did not prompt laughter. \"This study shows that humor is really more complex than people make it out to be,\" senior author Charles Emery, a professor of psychology at Ohio State University, says in a statement. \"Yes, humor definitely has benefits, but the behaviors associated with humor in fact may not be good for all people all the time -- which is a useful thing to know.\" COPD is a chronic, progressive disorder characterized by difficulty breathing, and especially in expelling air from the lungs.