The Interactive Influence of Life Stressor and Sleep Disturbance on Depression: A Cross-Sectional Examination on Chinese and Japanese University Students

Abstract

The present study investigated how life stressors and sleep disturbances interactively affect depressive symptoms among university students. Based on a hypothesis that sleep disturbance can be a cause of depression, a statistical model is established which expects that life stressors impact depressive symptoms indirectly rather than directly by increasing sleep disturbances, while sleep disturbances directly work to increase depressive symptoms. Three groups of university students, Japanese (N = 784) and Chinese (N = 311) students in their native countries and Chinese students living in Japan (N = 82), were tested to reveal whether the model fits to all of them and whether there are cultural differences on life stressors and sleep disturbance. The participants responded to a set of questionnaires measuring the extent of depressive symptoms (BDI-II), sleep disturbance symptoms (insomnia, hypersomnia, and nightmare), and experience of life stressors. Japanese students reported more severe depressive symptoms than both groups of Chinese, but the Chinese have had experienced more life stressors than Japanese. Also, Japanese students reported severe hypersomnia symptoms than both groups of Chinese but the trend was reversed for nightmare. The statistical model of depression fitted well for all participant groups. Although experience of life stressors showed direct impact on depression, its indirect effect via sleep disturbance was stronger than its direct effect. This suggests that addressing sleep disturbance symptoms at earliest opportunity is an effective procedure to prevent onset of depression for university students. Implementing sleep education programs could be especially effective for this population.