The DST was Bailey's invention, a cocktail of barbiturates to put patients into a coma lasting up to 39 days, while also administering electro-convulsive therapy (ECT). Bailey likened the treatment to switching off a television; his self-developed theory was that the brain, by shutting down for an extended period, would "unlearn" habits that led to depression, addiction and other psychiatric conditions. Bailey claimed to have learnt DST from psychiatrists in Britain and Europe, though it was later found that only a mild variant was used there, sedating traumatised ex-soldiers for a few hours at a time, not the median 14 days under which Bailey and his colleague Dr John Herron subjected their 1127 DST patients at Chelmsford between 1963 and 1979.