Suzanne O'Sullivan in The Telegraph:
I qualified as a doctor in 1991. I knew from an early stage in my training that I wanted to be a neurologist. When I made that choice I thought I knew what it meant: I enjoyed the detective drama, unravelling the mysteries of how the nervous system communicates its messages, and learning all the things that can go wrong. I started my first training post in neurology in 1995, expecting to look after people who had diseases of the brain and nerves and muscles; conditions such as multiple sclerosis, stroke, migraine and epilepsy. I could not have predicted how far I would find myself drawn into the care of those whose illness originated not in the body, but in the mind. Examples of how the mind affects the body are everywhere. Some are commonplace: tears are a physiological response to a feeling. Blushing occurs when the blood vessels of the head and neck dilate and become infused with blood. It is an instantaneous and uncontrollable physical change seen on the surface but reflecting a feeling of embarrassment or happiness that is held inside.
The word psychosomatic refers to physical symptoms that occur for psychological reasons. Tears and blushing are examples of this, but they are normal responses that do not represent illness. It is only when psychosomatic symptoms go beyond the ordinary and impair our ability to function that illness results. Modern society likes the idea that we can think ourselves better. When we are unwell, we tell ourselves that if we adopt a positive mental attitude, we will have a better chance of recovery. I am sure that is correct. But society has not fully woken up to the frequency with which people do the opposite – unconsciously think themselves ill.
More here.