Low sleep quality in major depressive disorder is associated with thinning and decreased functional connectivity of the insular cortex: Insular cortex and sleep quality in depression

•Sleep disturbances are common in depression. Poor sleep quality can exacerbate symptoms of depression and effective treatment of insomnia improves the core symptoms of depression. However, the neurobiology of sleep disturbances in depression is poorly understood. Our study reveals a connection between poor sleep quality in depressed patients and both thinner cortex and reduced functional connectivity in the insular region. This suggests the insula's potential involvement in sleep regulation and its disruption in major depressive disorder. The insular cortex, pivotal for emotional and salience processing, could serve as a neurobiological link between low mood and systemic hyperarousal, common in depression and insomnia.