Cluster headaches are ‘the most painful condition on the planet’. Sufferers are going to extreme – and secretive – measures for relief

The condition is more excruciating than childbirth or gunshot wounds, but little understood. An online community of ‘clusterheads’ are self-experimenting with psilocybin – with promising results Peter was working late, watching two roulette tables in play at a London casino, when he felt something stir behind his right eye. It...