Yet another reason to keep your attendees in an upbeat mood: It can prevent colds. Between travel and hand-shaking, meetings can be serious disease-spreaders. From the article:
Each person was quarantined in a separate room and monitored for 5 or 6 days. Although a positive emotional style bore no relation to whether participants became infected, it protected against the emergence of cold symptoms. For instance, among people infected by the influenza virus, 14 of 50 (28 percent) who often reported positive emotions developed coughs, congestion, and other cold symptoms, as compared with 23 of 56 infected individuals (41 percent) who rarely reported positive emotions.
The article suggests that it's not necessarily situational, that generally happy people tend to have fewer symptoms, but if you can make them happier, maybe there will be less tissue consumption on the show floor.