Effects of rain sound on mental arithmetic, mood, autonomic nervous activity, and salivary cortisol

Effects of rain sound on mental arithmetic, mood, autonomic nervous activity and salivary cortisol was evaluated, by examining characteristics of autonomic and endocrine system responses to a psychological stressor (Mental arithmetic), along with associated mood change and mental arithmetic performance under rain sound condition and control one, in 24 female college students (18 to 23 years old). We employed profile of mood states and visual analogue scale to assess mood, and employed heart rate variability, systolic and diastolic blood pressure to assess autonomic nervous activity, and salivary cortisol response to mental arithmetic to assess hypothalamo-pituitary adrenal axis reactivity. Repeated measures ANOVA revealed decrease of basal anger-hostility, and decrease of salivary cortisol secretion response to mental arithmetic, along with increased accuracy of mental arithmetic, and with some tendency of sympathetic predominance, under rain sound condition. These results suggest that rain sound would raise arousal level with coolness, and may increase accuracy of mental arithmetic.