It has been suggested that some factor or a combination of factors, such as a genetic susceptibility, biologic abnormalities, chronic sleep deprivation, or trauma, causes generalized hypervigilance , an amplification of sensation. People with this condition are over-sensititive to external stimulation and are preoccupied with the sensation of pain. One study compared three groups of individuals: those with FM; patients with rheumatoid arthritis; and people without these disorders. They were given a questionnaire to assess their response to pain and noise. Of the three groups, the FM patients were least tolerant and most attentive to such stimuli.