Sleep quality components and mental health: Study with a non-clinical population.

The deconstruction of sleep quality into its particular components may help to specify how each one of them influences mental health. Thus, to detail the understanding of the relationship between sleep quality and mental health, our study aims to assess the relationship between each component of the Pittsburgh Sleep Quality Index (PSQI) and depression, anxiety and stress. Also, we intend to analyse the moderating effects of gender, age and country on these relationships. The instruments PSQI and Depression Anxiety Stress Scale (DASS-21) were applied to a non-clinical population of 1552 participants from three different countries (Portugal, Spain and Brazil), aged over 18 years old. We estimated a multivariate regression model with AMOS Graphic 21.0 to test the seven proposed research hypotheses. The adjusted model explains 14.0%, 21.0% and 19.3% of the variances of depression, anxiety and stress, respectively. The conclusion of this study demonstrates that, with the exception of subjective sleep quality, all the other six components of the PSQI individually relate to mental health in non-clinical populations and that country is a significant moderator of these relationships.