Poor sleep quality has been linked to both poor psychological and physical well-being. Mood and anxiety levels are affected by poor quality sleep, and the relationship between these variables appears to be mediated by a tendency to depersonalize or not. This study examines these relationships in 112 Adults (Female = 82, Male = 30), via an online study. The Pittsburgh Sleep Quality Index, Patient Health Questionnaire4, Cambridge Depersonalization Scale-9, and Patient Health Questionnaire-15 were administered using the Gorilla platform. The following variables were analyzed using correlation statistics, and mediation analyses: sleep quality, anxiety, depression, somatic pain, and depersonalization. Poor sleep quality was associated with higher levels of all psychological variables. As predicted, depersonalization mediated the relationship between sleep quality and anxiety, depression and somatic concerns. The findings indicate that sleep quality and the mediating effect of depersonalization have a significant impact on psychological well-being in adults.