In just the last few years, AI chatbots have become routine aspects of many people’s everyday lives. They are being used as search engines, agony aunts and sources of companionship. In rare cases though, AI chatbots have sent users down a dark path. In a new BBC investigation, population correspondent Stephanie Hegarty speaks to people who have experienced delusions after talking to chatbots – including one man who grabbed a hammer and prepared for war after his chatbot told him it was sentient.