As a physicist, I was surprised by coming to realization that placebo can actually affect physical illnesses. I searched on the internet, but explanations for mechanism of placebo were either unclear (I am a layman in medical science after all) or not convincing enough. So I would appreciate any clarification (or even some references) on this subject. I am asking for a widely accepted theory (or at least a hypothesis) behind physical mechanism of it.
For example from this study:
Several research studies have demonstrated the placebo effect's role as a powerful determinant of health in certain disease conditions. Migraines, joint pain, arthritis, asthma, high blood pressure, and depression are some disease conditions that are more sensitive to the placebo effect.
Identifying a physiological basis for the placebo effect may open doors to modulating processes that can improve mental and physical health.
Or from here:
The results suggest that placebo interventions can improve physical disease processes of peripheral organs more easily and effectively than biochemical processes
Am I misunderstanding something and placebo doesn't affect physical health?