0:00:06.605,0:00:11.018 In 1996, 56 volunteers took part[br]in a study 0:00:11.018,0:00:14.653 to test a new painkiller called[br]Trivaricaine. 0:00:14.653,0:00:18.773 On each subject, one index finger[br]was covered in the new painkiller 0:00:18.773,0:00:21.569 while the other remained untouched. 0:00:21.569,0:00:25.211 Then, both were squeezed[br]in painful clamps. 0:00:25.211,0:00:29.526 The subjects reported that the treated[br]finger hurt less than the untreated one. 0:00:29.526,0:00:31.386 This shouldn't be surprising, 0:00:31.386,0:00:34.843 except Trivaricaine wasn't actually[br]a painkiller, 0:00:34.843,0:00:39.066 just a fake concotion [br]with no pain-easing properties at all. 0:00:39.066,0:00:43.073 What made the students so sure[br]this dummy drug had worked? 0:00:43.073,0:00:45.842 The answer lies in the placebo effect, 0:00:45.842,0:00:47.286 an unexplained phenomenon 0:00:47.286,0:00:51.840 wherein drugs, treatments, and therapies[br]that aren't supposed to have an effect, 0:00:51.840,0:00:53.405 and are often fake, 0:00:53.405,0:00:56.465 miraculously make people feel better. 0:00:56.465,0:01:00.496 Doctors have used the term placebo[br]since the 1700s 0:01:00.496,0:01:05.175 when they realized the power of[br]fake drugs to improve people's symptoms. 0:01:05.175,0:01:08.086 These were administered when proper drugs[br]weren't available, 0:01:08.086,0:01:11.371 or if someone imagined they were ill. 0:01:11.371,0:01:15.522 In fact, the word placebo[br]means "I shall please" in Latin, 0:01:15.522,0:01:19.127 hinting at a history of placating[br]troubled patients. 0:01:19.127,0:01:23.026 Placebos had to mimic the real treatments[br]in order to be convincing, 0:01:23.026,0:01:25.270 so they took the form of sugar pills, 0:01:25.270,0:01:26.625 water-filled injections, 0:01:26.625,0:01:29.492 and even sham surgeries. 0:01:29.492,0:01:33.871 Soon, doctors realized that duping people[br]in this way had another use: 0:01:33.871,0:01:35.743 in clinical trials. 0:01:35.743,0:01:39.894 By the 1950s, researchers were using[br]placebos as a standard tool 0:01:39.894,0:01:41.847 to test new treatments. 0:01:41.847,0:01:43.687 To evaluate a new drug, for instance, 0:01:43.687,0:01:46.553 half the patients in a trial might receive[br]the real pill. 0:01:46.553,0:01:49.902 The other half would get a placebo[br]that looked the same. 0:01:49.902,0:01:54.213 Since patients wouldn't know whether[br]they'd received the real thing or a dud, 0:01:54.213,0:01:56.242 the results wouldn't be biased, 0:01:56.242,0:01:57.879 researchers believed. 0:01:57.879,0:02:02.001 Then, if the new drug showed a significant[br]benefit compared to the placebo, 0:02:02.001,0:02:03.998 it was proved effective. 0:02:03.998,0:02:09.501 Nowadays, it's less common to use placebos[br]this way because of ethical concerns. 0:02:09.501,0:02:13.038 If it's possible to compare a new drug[br]against an older version, 0:02:13.038,0:02:14.908 or another existing drug, 0:02:14.908,0:02:18.645 that's preferable to simply giving[br]someone no treatment at all, 0:02:18.645,0:02:21.190 especially if they have a serious ailment. 0:02:21.190,0:02:26.243 In these cases, placebos are often used[br]as a control to fine-tune the trial 0:02:26.243,0:02:29.811 so that the effects of the new versus[br]the old or alternative drug 0:02:29.811,0:02:33.096 can be precisely compared. 0:02:33.096,0:02:37.503 But of course, we know the placebos[br]exert their own influence, too. 0:02:37.503,0:02:38.952 Thanks to the placebo effect, 0:02:38.952,0:02:41.954 patients have experienced relief [br]from a range of ailments, 0:02:41.954,0:02:43.273 including heart problems, 0:02:43.273,0:02:44.422 asthma, 0:02:44.422,0:02:46.130 and severe pain, 0:02:46.130,0:02:50.126 even though all they'd received[br]was a fake drug or sham surgery. 0:02:50.126,0:02:52.766 We're still trying to understand how. 0:02:52.766,0:02:54.765 Some believe that instead of being real, 0:02:54.765,0:02:58.625 the placebo effect is merely confused[br]with other factors, 0:02:58.625,0:03:03.129 like patients trying to please doctors[br]by falsely reporting improvements. 0:03:03.129,0:03:04.123 On the other hand, 0:03:04.123,0:03:07.539 researchers think that if a person [br]believes a fake treatment is real, 0:03:07.539,0:03:12.208 their expectations of recovery actually[br]do trigger physiological factors 0:03:12.208,0:03:14.241 that improve their symptoms. 0:03:14.241,0:03:18.487 Placebos seem to be capable of causing[br]measurable change in blood pressure, 0:03:18.487,0:03:19.361 heart rate, 0:03:19.361,0:03:23.280 and the release of pain-reducing[br]chemicals, like endorphins. 0:03:23.280,0:03:28.914 That explains why subjects in pain studies[br]often say placebos ease their discomfort. 0:03:28.914,0:03:31.493 Placebos may even reduce levels[br]of stress hormones, 0:03:31.493,0:03:32.974 like adrenaline, 0:03:32.974,0:03:35.995 which can slow the harmful effects[br]of an ailment. 0:03:35.995,0:03:39.954 So shouldn't we celebrate[br]the placebo's bizarre benefits? 0:03:39.954,0:03:41.439 Not necessarily. 0:03:41.439,0:03:43.975 If somebody believes a fake treatment[br]has cured them, 0:03:43.975,0:03:48.586 they may miss out on drugs[br]or therapies that are proven to work. 0:03:48.586,0:03:51.774 Plus, the positive effects [br]may fade over time, 0:03:51.774,0:03:53.503 and often do. 0:03:53.503,0:03:55.735 Placebos also cloud clinical results, 0:03:55.735,0:03:58.821 making scientists even [br]more motivated to discover 0:03:58.821,0:04:01.491 how they wield such power over us. 0:04:01.491,0:04:04.424 Despite everything we know about[br]the human body, 0:04:04.424,0:04:07.450 there are still some strange[br]and enduring mysteries, 0:04:07.450,0:04:09.184 like the placebo effect. 0:04:09.184,0:04:13.404 So what other undiscovered marvels[br]might we contain? 0:04:13.404,0:04:15.622 It's easy to investigate the world[br]around us 0:04:15.622,0:04:18.746 and forget that one of its most [br]fascinating subjects 0:04:18.746,0:04:21.026 lies right behind our eyes.