Most people assume that for a placebo to have any chance of the being effective, the patient must be unaware that they are getting a placebo. But, surprisingly, many studies indicate the opposite. “A review of five studies, involving 260 patients, published last month found that ‘open-label’ placebos – those that patients know contain no active medication – can improve symptoms in a range of conditions.” From The Guardian: I knew they were sugar pills but I felt fantastic.