Cognitive activation theory of stress, sensitization, and common health complaints.

According to the cognitive activation theory of stress (CATS), a formal system of systematic definitions, the term "stress" is used for stress stimuli, the stress experience, the nonspecific, general stress response, and the experience of the stress response. The stress response is normal, healthy, and necessary alarm. If sustained there may be a risk of illness and disease. The level and duration of the alarm depend on the expectancy of the outcome of stimuli and the specific responses available for coping. The most common health complaints are subjective health complaints like muscle pain, tiredness and mood changes. These are normal aches of short duration and low intensity for most people. For some the pains and complaints are substantial and longlasting with serious implications for functioning. There are no sharp or obvious limits in the distribution of health complaints, separating "normal" and endurable pain and complaints, and intolerable complaints that need professional help. These conditions are most often unspecific, and are the most common reason for encounters with health professionals, and the most frequent reason for sick leave and disability. There is a striking comorbidity for all these conditions. This may be explained by psychobiological sensitization within neural loops, maintained by sustained activation, which has been suggested as a mechanism for these conditions.