In addition there is a need to describe the patients participating in the program. The aetiology of complex symptom disorders is poorly understood and the role of genetics and stress is not translatable to a complex symptom population. This complicates the transition from current biological research to a clinical use regarding these patients. If the investigators can assist in understanding how these patients, who are multiusers of health care and have received sickness benefit for a long time, develop their disorders and symptoms, it will be of great importance to the Norwegian community. Therefore the study consists of multimodal measurements of the patients before, during and after a rehabilitation programme at Hysnes Rehabilitation Centre. These measures include genotype, saliva cortisol, medical-, psychological-, physiological diagnostics and work related factors.