Vulnerability to Stress-Related Sleep Disturbance and Insomnia: Investigating the Link with Comorbid Depressive Symptoms.
Greater sleep difficulty following a challenging event, or a vulnerability to stress-related sleep disturbance (i.e., sleep reactivity), is characteristic of insomnia. However, insomnia is rarely observed in isolation; rather it is frequently seen in combination with other problems, such as depression. Despite the link between depression and increased sensitivity to stress, relatively little is known about the role sleep reactivity has in explaining variability in depressive symptoms. Therefore, the current study examined whether sleep reactivity was associated with depressive symptoms, and whether this relationship was mediated by insomnia. We assessed sleep reactivity, insomnia, and depressive symptoms among 2250 young adults (1244 female; Mage = 23.1, SDage = 2.97) from the Colorado Longitudinal Twin Study and Community Twin Study. Results indicated that greater sleep reactivity was significantly associated with elevated depressive symptoms, and that this link was partially mediated by insomnia. This is one of the first studies to demonstrate an independent association between sleep reactivity and depressive symptomatology. These findings suggest that a greater sensitivity to stress-related sleep disturbance may also be a predisposing factor to depression, and highlight the need for a better understanding of sleep reactivity, as it may represent a more global vulnerability construct.