This study presents an explanatory Ordinary Linear Regression Model for predicting wellbeing in the use of smart screen devices among children and youngsters in Spain, using a database of microdata for a total of 23,860 national representative households and some 6,106 total cohabiting minors under 15 years of age. The World Health Organization actively recommends children and youngsters to spend less hours in front of smart screen devices and encourages substituting them with more active play and direct socialisation. The main purpose of our research is to study the impact of the use of these devices on mental and physical well-being, sleep pattern, and the potential explanatory effects. To address the analysis, we contrasted the modelisation model proposed with microdata provided in the 2017 version of the National Health Survey in Spain. We performed a series of ordinary least square regression models OLS, obtaining significant information on the effects and risks excessive use of smart screen devices may be inflicting on children and adolescents in Spain. As a main result, we contrasted with the data and the modelisation that those individuals who use these devices more intensively have higher risk of mental health problems, significantly reduced sleeping hours and have a higher chance of suffering physical health problems such as obesity.