Placebo effect

Doctors have long noticed that people tend to get better whenever they take a treatment they believe might help them. Even treatment with placebo—a nonmedicinal substance such as a sugar pill—can make people feel better if they believe it is medicine.

Also, when people believe they are taking an effective treatment, they may be more conscientious about taking other steps that can help them, such as improving their diet and increasing exercise. This can produce benefits even if the treatment itself is ineffective.