The Effect of Light on Negative Emotion and Cognitive Regulation in Individuals with Depressive Tendencies

Light has been demonstrated to influence transient mood states in healthy populations and can be used as a treatment for clinical mood disorders. However, it is still interesting to know whether stimulus with relatively low light levels can moderate the transient mood state of people with depressive tendencies, and what are the effects respectively from light levels and light color. In this study, 10 subjects with depressive tendencies were recruited and screened to receive a typical lighting intervention, including five crossover conditions with the 300 lx-isoluminance groups (red, 6500 K-white, blue) and 6500 K-isospectral groups (50 lx, 300 lx, and 1500 lx). Negative cognitive bias, high-frequency heart rate variability, and subjective emotion were measured at different stages during the lighting intervention. Statistical results demonstrated that the lighting condition of 1500 lx-6500 K was associated with a transient positive mood state (p < 0.001) and had a significant positive moderating effect on the negative cognitive biases compared with the other groups (p = .017). Colored lights are more likely to trigger negative emotions and negative cognitive biases.