LED Colors and Worker Stress Response after a Flower Arrangement Activity

We investigated the effects of different colors of light-emitting diodes (LEDs) on worker stress response, before and after a flower arrangement (FA) activity. 16 office workers performed FA under various lighting conditions: darkness, white (4,500 K), red, blue, green, magenta, cyan, and yellow; no FA was performed in the darkness condition. To identify significant differences among the different lighting conditions, heart rate (HR), blood pressure, and heart rate variability (HRV), consisting of standard deviation of the normal-normal intervals, total power, and ratio of low frequency to high frequency, were measured before and after FA. Salivary cortisol was analyzed immediately after FA. The correlations among HR, HRV, and cortisol showed that the blue and green lights positively affected stress responses and caused considerable reduction in stress. However, there was only a slightly significant difference among other lighting colors, although individual lights may impact one or more parameters. These findings show that our study can be effectively used to enhance horticultural therapy through the constructive assistance of LED lighting colors.