LAUSR

OBJECTIVES This study aimed to compare the effectiveness of paced breathing (PB) versus su-soku practice (spontaneous breathing with counting numbers) on autonomic function and brain activity and examine the associations between personality traits, brain activity, and autonomic function. DESIGN A three-way crossover study design. SETTING Thirty healthy Korean participants (15 men: 28.5±4.7 years; 15 women: 27.7±4.8 years) were asked to answer the Korean version of the 125-Temperament and Character Inventory (TCI). Three-way crossover design included normal PB (0.25Hz), slow PB (0.1Hz), and su-soku practice. Participants were randomly assigned to one of three groups (group A: su-soku/normal PB/slow PB; group B: normal PB/slow PB/su-soku; group C: slow PB/su-soku/normal PB). MAIN OUTCOME MEASURES The Korean version of the 125-TCI scores, electroencephalography (EEG), heart rate variability (HRV), and respiratory curve data. RESULTS EEG parameters between normal PB, slow PB, and su-soku showed no significant differences. High frequency and approximate entropy during normal PB and su-soku were higher than those during slow PB. Alpha band power related to well-focused alertness had strong negative correlations with the standard deviation of R-R intervals and square root of the mean of the sum of the squares of differences between adjacent R-R intervals during su-soku practice, while theta band power related to drowsiness had strong positive correlations with very low-frequency power during normal PB. Reflective and analytical individuals tended to be highly focused and alert during su-soku and normal PB, while anxious and unwilling individuals tended to focus on counting in and be drowsier during normal PB. CONCLUSIONS This study's findings suggest that the association between brain activity and autonomic function is affected by meditation type and personality traits.