Circadian variations of the subjective habituation to cold pain

Journal/Book: J. interdiscipl. Cycle Res. 23: 222-224 (1992). 1992;

Abstract: (Institut für Arbeitsphysiologie und Rehabilitationsforschung der Philipps-Universität Robert-Koch-Str. 7a. D-3550 Marburg/Lahn F.R.G.) In contrast with the numerous functions under resting conditions little is known up to now of the circadian variations of adaptive capacities of the human organism. In 1975 we were able to show that the steepness of habituation (1) of the socalled Cold-Pressure-Reaction (2) of the diastolic blood pressure during intermittent exposures of the hands to 4 °C cold water bathes undergoes a circadian variation passing its maximum around noon (3). From these experiments some evidence was obtained that subjective cold pain also undergoes a circadian variation. Methods In order to trace this question more systematically in the present study 10 healthy subjects dipped one hand in a water bath of 4 °C as long as they were able to tolerate the cold pain induced. By means of a special mechanical device the depth of immersion was kept constantly. The time up to the onset of cold pain (latency time) and the duration of tolerating the cold pain (tolerance time) were measured. After rewarming the hand for 1 min each in a water bath of 31.5 °C the cold exposure was repeated up to 12 times. To measure subjective habituation the slopes of the fairly linear increases of latency and tolerance times were calculated. Each subject repeated this procedure intermittently at 6 different times of day (starting at 3.00 7.00 11.00 15.00. 19.00 and 23.00 hours respectively). Minimal intervals were 48 hours and the sequences were varied by chance. Moreover pulse and respiratory rate were registered under resting conditions in order to control circadian phase and autonomous state respectively. Results and Discussion The mean daily courses of the individual . . .

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