Essays in Health Economics This proposed thesis comprises essays focusing on pressing social challenges in public health, with significant repercussions for individuals, households, and economies. Specifically, it investigates two key issues: population ageing and the impact of legal and illegal substance abuse. Through the use of natural experiments, these essays aim to uncover behavioral responses to population ageing and assess the effects of addictive substance accessibility on mental health, labor market performance, black market dynamics, and substance consumption. The student will collaborate closely with the Health Economics, Policy, and Innovation Institute (HEPII) at Masaryk University, actively participating in projects led by the Department of Economics and HEPII.