Background From a theoretical perspective, several studies indicate that happiness and health are—in some extent—interrelated. Despite the mechanisms explaining the relationship between happiness and health, there is still no consensus regarding this link. Using recently collected primary data, this study aims to examine the relationship between happiness and health, and identify potential heterogeneity in the association depending on socioeconomic status (SES).

Methods This study draws on data from a nationally representative cross-sectional survey, conducted by the Greek National School of Public Health in 2015. We applied an instrumental variable (IV) approach to address the endogeneity, arising from the simultaneous determination of happiness and health. Controlling for several confounders (ie, socioeconomic, demographic, lifestyle, social capital variables) we employed several IV models, including two-stage least squares, IV probit and bivariate probit models.

Results We report strong evidence of a relationship between happiness and health. This association remains strong after correcting for endogeneity, and is robust across different specifications. Further, we find a positive relationship between happiness and self-rated health (SRH) for low educated, but not for high educated. Similarly, we find a strong relationship between happiness and health for the lower socioeconomic strata, but not for the higher ones.

Conclusions Overall, we show that happiness is positively associated with health. Further, happiness significantly influences SRH in low-SES individuals, but this association wanes for the higher socioeconomic strata. This finding has significant implications for health promotion, prevention and public health, and suggests that policymakers have a wider array of choices for improving health and tackling health inequalities.