Susannah Cahalan

For centuries, doctors have struggled to define mental illness – how do you diagnose it, how do you treat it, how do you even know what it is? In search of an answer, in the 1970s a Stanford psychologist named David Rosenhan and seven other people – sane, normal, well-adjusted members of society – went undercover into asylums around America to test the legitimacy of psychiatry's labels. Forced to remain inside until they'd 'proven' themselves sane, all eight emerged with...