Effect of ambient temperature changes in autonomic responses.

Effect of moderate changes in ambient temperature on autonomic activity was studied in male medical students. Autonomic function tests, i.e. Valsalva ratio, standing-to-lying ratio (S/L ratio), cold pressor response (CPR) and resting heart rate were carried out at two different ambient temperatures of 37.45 degrees +/- 0.52 degrees C and 32.54 degrees +/- 0.65 degrees C. At lower ambient temperature, there was decrease in the Valsalva ratio, increase in S/L ratio and lesser augmentation of systolic and diastolic blood pressure in CPR as compared to that at higher ambient temperature, indicating alteration in autonomic response with moderate changes in ambient temperature.