Simic, N., Manenica, I. (1998). Changes in Some Psychophisiological
     Variables during Menstrual Cycle, RADOVI - Razdio FPSP , 36(13),

   The aim of the investigation, which included 100 female subjects aged 18-24 years, was to find out whether the changes in some psychophisiological variables during the menstrual cycle can be attributed to hormonal changes in organism. The investigation included measurements of body temperature, pulse rate, state anxiety, reaction time to one, two and four light stimuli, together with the assessment of task difficulty. The subjects were at different stages of the menstrual cycle (menstrual, folicular, ovulatory, luteal and premenstrual phase). The results showed that changes in body temperature followed the changes in hormone progesteron during the five phases, while the changes in other variables could not be readily attributed to changes in the hormone level.
    The results also showed that state anxiety was significantly correlated with the two phisiological variables (body temperature, pulse rate) and the assessment of task difficulty. It could, therefore, be said, that state anxiety reflected changes in the state of organism. It seems that changes in some efficiency aspects (reaction time) were determined by some more complex interactive processes between hormonal and psychophisiological variation during the menstrual cycle.