In the few years since its launch, TikTok has already altered the face of the social media landscape, attracting more than 1 billion users and leading competitors to replicate some of its most unique features. The impact of that explosive growth and the ‘TikTok-ification’ of the internet at large on social media users remains little understood, experts warn, exacerbating concerns about the impact of social media on our habits and mental health. “It’s embarrassing that we know so little about TikTok and its effects,” said Philipp Lorenz-Spreen, a research scientist at the Max Planck Institute for Human Development in Berlin....