Figure 1.

The humoristic intervention was done by Pello the clown (panel A), a professional humor consultant experienced with patients affected by chronic diseases. Panel B shows a typical scene during the humor intervention. The intervention was done in small groups with roughly 6 participants. Thus, Pello could directly interact with all participants and varied his performance in function of individual responses. The show was optimized to induce as much physical laughter as possible. Different accessories like puppets, and red plastic noses were used during the intervention, which took place on the hospital ward.