I have read Jo Marchant's "Cure" and Anne Harrington's "The Cure Within". Both get into the subject of "placebos" and "nocebos", the subject that is sometimes referred to as "mind-body" medicine. There are several posts in this blog that refer to placebos, often described as "inert medicines" or pills that supposedly are not medicine but are described as such or given as such and can still have a positive effect.
https://fearfunandfiloz.blogspot.com/search?q=placebo
There are many experiments where a doctor gives me some sort of sugar pill but tells me the pill is a powerful medicine. Later, I am better off physically. This kind of thing can happen even when the doctor tells me that a) the pill is inert and contains no special medicine but b) it will make me better.
A woman I know sometimes has trouble falling asleep or staying asleep for long enough or returning to sleep when she has awakened. She knows I am interested in the subject and have purchased openly labeled placebo pills from Amazon. They are blue and white capsules that are empty. Since she is tired of having sleep troubles, she wisely took some of those capsules and is taking them when needed. She reports they seem to have helped.