Variations in mood and performance associated with the menstrual cycle.

A group of women, who were not using oral contraceptives, kept daily records of basal body temperature, mood and energy for periods varying from six months to two years. The women reported to the laboratory weekly at the same time to be tested on concept formation, digit symbol substitution, choice reaction time and rotor pursuit tasks. The mood, energy and performance data were normalised to a standard 28 day cycle firmly anchored around menstruation and ovulation, which was pinpointed by using the temperature curves. Mood and energy were both found to be high around ovulation but low paramenstrually. No significant differences associated with different phases of the menstrual cycle, were found in performance on the digit symbol substitution and rotor pursuit tasks but performance on concept formation and choice reaction time was found to be good premenstrually and preovulatory but deteriorated following ovulation and during menstruation. It is hypothesised that changes in estrogen levels may be responsible for the mood and energy levels observed; that the changes in performance are a function of the information load of the task and that this may be due to fluctuations in arousal across the cycle or to the direct effect of gonadotrophins upon information processing. The generalis-ability of the data obtained from the sample studied was investigated using a menstrual questionnaire which was administered to 300 students.