Over 100,000 copies sold! When Your Brain on Porn was first published the porn industry and its lobbyists reacted with outrage. How could a commodity so popular - and so profitable - be a problem? But evidence of porn's addictiveness has been accumulating ever since. In February 2022 the peer-reviewed journal Psychological Medicine published a large-scale, longitudinal study that confirmed what many users and former users of digital pornography had figured out for themselves: 'porn - a male-dominated industry that targets a male-dominated audience - is associated with the erosion of the quality of men's sex lives.' In the same month the World Health Organization issued a clarification to its diagnosis of Compulsive Sexual Behaviour Disorder. Contrary to the claims of a vocal group of sexologists, the WHO insisted that the disorder 'may be expressed in a variety of behaviours, including sexual behaviour with others, masturbation, use of pornography, cybersex (including internet sex), telephone sex, and other forms of repetitive sexual behaviour.' Compulsive porn use is now recognised as a pathology by the world's leading health experts, in the most widely used diagnostic manual on the planet. This should not be surprising. As soon as high-speed internet became widely available a decade ago, growing numbers of people began to worry that their porn use was running out of control. Far from preparing them for fulfilling relationships, viewing an endless stream of porn videos led to unexpected adverse effects. Perhaps most surprisingly, for the first time in history erectile dysfunction was becoming a pervasive problem for young men. This led to one of the largest informal experiments in the history of science. Tens of thousands of people have tried abstaining from sexually stimulating material in a process they call 'rebooting'. Many of them reported startling changes, from improved concentration and elevated mood to a