Haematological changes during acute mental stress.

To study haematological effects of emotional stress, blood samples were obtained from 29 healthy, normotensive, non-smoking males aged 20-34 years before, during and after 10 min of mental arithmetic. There were significant increases in peripheral blood cell count, haemoglobin concentration, and haematocrit in response to mental stress. Parallel to these changes significant increases in heart rate, and systolic and diastolic blood pressure were observed. The relative increments of leucocyte (8%) and platelet (3.5%) count were significantly higher than the increase in haemoglobin concentration (2%). There was a significant positive correlation between the blood pressure increase and the mobilization of leucocytes, whereas the increase in erythrocyte count, haemoglobin concentration, and haematocrit showed significant positive correlations with heart rate reactivity. It is concluded that mental stress causes an increase in leucocyte and platelet count that could not solely be accounted for by the concurrent haemoconcentration.