Sleep trackers monitor every move. Biohackers swear by red light therapy, supplements and continuous health monitoring. Smart devices track blood sugar, fitness and recovery, promising longer, healthier lives. While looking after your health makes sense, some people become caught in a relentless cycle of self-optimization. In this edition of In Good Shape, we meet dedicated self-improvers known as biohackers, and ask researchers and doctors a simple question: what really works, and where are the risks?