(1) Aims: To explore temporal trends 2010-2018 of well-being among Italian adolescents and to evaluate potential explanatory factors. (2) Methods: Italian nationality representative samples of students aged 11, 13, and 15 years were recruited in 2010, 2014, and 2018; Health Behaviour in School-aged Children (HBSC), for an overall number of 165,000 teenagers. Multivariable logistic regression models were performed to fit the trends over time of life satisfaction (LS), psychological (PSY-HC) and somatic health complaints (SOM-HC) considering the contextual factors: school work pressure, social support (family, school, peers), socioeconomic status, geographic area, and immigration background; (3) Results: From 2010 to 2018 while LS was steady, health complaints increased, mainly for PSY-HC, in all age and gender groups. Trend of PSY-HC affected mainly 15-years-olds: rates among boys varied from 29.6% to 35.9% (OR: 1.13, 95%CI: 1.02-1.25); among girls from 49.1% to 63.3% (OR: 1.56, 95%CI: 1.42-1.72). High school work pressure and poor social support play a central role in worsening well-being outcomes; (4) Conclusions: Our findings pictured a remarkable worsening trend of teenagers' well-being, especially among 15-year-old girls. Further research will be required to investigate this breaking up of the connection between psychophysical symptomatology and cognitive perception of life satisfaction.
Keywords: Dual Factor Model; HBSC; adolescents; life satisfaction; mental health; psychological health complaints; temporal trend; well-being.