The underlying changes in biological processes that are associated with reported changes in mental and physical health in response to yoga breathing (prānāyāma) have not been systematically explored yet. In this study, the effects of a yoga breathing program on prefrontal EEG were tested with middle-aged women. Participants were collected as volunteers and controlled into two groups. Two channel EEG was recorded in the prefrontal region (Fp1, Fp2) from the yoga breathing group (n=17) and control group (n=17). QEEG quotients were transformed from the EEGs and analyzed by the ANOVAs on gain scores. As a result, α/δ (left, right) and CQ (correlation quotient) for yoga breathing participants were significantly decreased compared to control group (p〈.05). α/βH+α/δ (left, right) were increased significantly (p〈.05). For those significantly changed QEEG quotients, the interaction effects of Group x prefrontal alpha (α) and beta (β) asymmetry were tested. Only the α asymmetry showed main effect on the gain score of α/βH+α/δ (right) with F (1, 34)＝5.694 (p〈.05). Pearson's correlation coefficient between α asymmetry and gain score of α/βH+α/δ (right) was .374 (p〈.05). The gain score of α/βH+α/δ (right) was increased for the right α dominance of yoga breathing group. On the contrary it was decreased for the left α dominance of yoga breathing group as well as the control regardless of the dominance. The result of this study implies that yoga breathing increases stress resistance and is effective in the management of physical stress. Emotionally relaxed people may have greater instantaneous stress reduction after yoga breathing. Moreover, yoga breathing could be also beneficial for depressed who may be more vulnerable to stress.

• Eunmi Kim(Department of Integrative Mind-Body Healing, Seoul University of Buddhism; Institute of Complementary and Integrative Medicine, Seoul National University) Corresponding Author