Poor sleep quality influences emotional evaluations even after controlling for depression

The relation between insomnia and depression is indeed a very important issue in clinical sleep research. For this reason, in our article we specifically carried out extensive and compelling control analyses, overlooked by the authors, to exclude that the between-groups differences in the evaluation of pictures were affected by depression. Neither the correlational analysis (Pearson’s r) nor the analysis of covariance (ANCOVA) with Beck Depression Inventory (BDI) scores as covariate on all dependent variables showed that BDI scores were responsible for the observed effects. In particular, the crucial interaction on ΔValence involving the factor Group remained significant even after the covariance of depression scores. Indeed the covariate was not significant for any variable. ANCOVA with depression as covariate only affected some of the main effects for Valence. This means that depressive symptoms may affect changes of pictures rating for both valence and arousal, but this effect is independent of the group. In other words, as stated on p. 868, although the groups differ in terms of BDI score, the impact of poor sleep on affective valence survived the statistical control of depressive symptoms, which indicates that the effects are not to be ascribed to depressive mood, but to a specific influence of poor sleep quality.