Essay in the classification of morning and evening types of activity in the light of the daily course of autonomically influenced body functions.

The present study is an attempt for an objective classification of types of activity by determining the daily periodicity of autonomically influenced body functions. On the basis of a questionnaire, the 23 probands of the test group were classified into morning types (7), evening types (11) and indifferent types (5). Then, for a period of 12h from 07(00) to 18(00), 17 different autonomically influenced parameters were recorded and their mean daily courses calculated separately for the probands of the morning and of the evening type. A comparison of the synchronous values showed that the greatest differences occur between the types at 10(00) and 17(00). At these times of the day, a multidimensional variance and discrimination analysis was carried out which resulted in a very good discrimination of the probands at 10(00) and in a satisfactory one at 17(00). At the same time, an evaluation of the individual parameters recorded was carried out according to their informative value. The most important parameters proved to be the vibration threshold, the R wave height, T wave height, peak time of the pupillogram and d.c. resistance of the skin. On the basis of these results, the classification of 10 probands of an independent test group was effected by a discrimination analysis. In 7 cases this resulted in an agreement with the classification according to the questionnaire.