671 Various studies of exam stress have shown that exam periods and exam situations are stressful for stu dents, which is especially true for oral exams. Some of the studies showed an increase in anxiety level, depres siveness and negative emotional states [1][2][3][4][5][6][7]. Some other authors who used cardiovascular, adrenocortical and immune system reactions, found an increase in cortisol level and immune suppressive effects which were related to exam stress [6,[8][9][10][11][12]. Stress induced immunosupresion increased the upper respiratory tract problems during exam periods [10,13]. High incidence of abdominal pains in students before exams was also related to exam stress [14], while lower exam scores related to higher levels of experienced exam stress [6]. Some authors [15] followed up changes in some psychophysiological variables before and after exams, where they found an increase in bad mood, lack of energy, bodily discomfort, somatic strain and restlessness of students during pre exam period. Their cortisol level and heart rate were increased after exams. Although there is a considerable number of studies on exam stress before and after exams, there is a paucity of studies, however, on physiological reac tions during the exam itself. One of such studies with continuous heart rate monitoring showed that oral exams were more stressful than written [8]. In a similar study, the authors [16] measured blood pressure and heart rate of students undergoing a medical licensing examination, five minutes before, three times during and five minutes after the exam. They found higher diastolic blood pressure and heart rate during the 1 The article is published in the original. exam, while systolic pressure did not change signifi cantly.Although heart rate proved to be a good indicator of overall stress, it does not clearly reflect changes in mental component of the load, which is one of the major components of exam stress. Better stress param eters are based on variability of cardiac R-R intervals (HRV) which are more sensitive to changes in mental load [17,18]. Some other studies showed a decrease in HRV parameters when mental load increased in tasks of various complexities [19][20][21]. Similar results were obtained in real working situations in offices, on pilots during flights, etc. [22][23][24]. Using cardiac activity parameters, our previous study [25] showed, not only could they be good indicators of stress during an exam, but they differentiated relative contributions of emo tional and mental stress components to overall of exam stress.Most of aforementioned investigations have shown that student' stress increases as their exams approach, but none of them gives any reference to previous exam experience and its effects on experienced exam stress. The only study of this kind was done on the first and second year medical students [26]. The authors found that the first year students had higher heart rate levels during oral exams, than their colleagues in the second year. This study ought to be taken with a res...
