Sleep quality and depressive symptoms: insights from a genetically informative design

According to the diathesis-stress model, the impact of environmental stressors on depression may vary depending on individual vulnerability (e.g., genetic predisposition). Sleep quality has been consistently linked to depression. However, the nature of this relationship is not yet fully understood. Our hypothesis was that there is a significant interaction between sleep quality and genetic vulnerability to depression that contributes to depressive symptomatology. The sample consisted of 1,147 participants from the Murcia Twin Registry (mean age: 55.8; SD: 7.6; females: 66%). Polygenic scores (PGS) for depression were calculated using LDpred2. The model that provided the best fit included sex, age, age ² , sleep quality, PGS for depression, and their interactions (AIC = 5637.4). Removing the interaction between sleep quality and PGS for depression resulted in a significant deterioration of model fit (AIC = 5644.7; P = 0.002). Our findings suggest that poor sleep quality may exert a greater influence on depressive symptoms in individuals with a higher genetic vulnerability to depression.