Researchers have discovered that employees perform better when their managers use humor. Laughter also seems to promote health: it lowers blood pressure, strengthens the immune system, relaxes the muscles, increases energy levels, and exercises the respiratory and cardiovascular systems.
Workers can use humor to make "no-win" situations more tolerable. When they deal with difficult or demanding customers or bosses, are required to enforce unpopular rules, or are put in circumstances that are beyond their control, laughter and shared jokes can help them stay positive.
In short, laughter can't change a difficult work situation, but it can help employees cope and improve their productivity and well-being.