Diurnal variation and individual differences in the perception of intractable pain.

Abstract 41 patients with intractable pain rated its intensity on a visual analogue scale at two hourly intervals, from 08.00 to 22.00, for seven successive days. These pain ratings were found to exhibit a marked diurnal variation. Differences in this diurnal variation were associated with the personality and sex of the patient, and with whether or not the patient typically went out to work during the day. For the majority of the patients the variations in reported pain intensity were unrelated to those in oral temperature and alertness ratings. The implications of these results for the effective relief of pain are discussed.