"Brainwashing" is one of those terms you'll often find portrayed in movies about religious cults or the CIA. It's usually perceived as fantastical and not even slightly real, and, in reality, there is no such thing as "brainwashing". However, there are certain things that can be used for psychological manipulation, indoctrination, and behavior modification. (Note: I found all of this out as I did research for Child of the Night Guild) Low-protein, high-sugar diet. A low-protein diet deprives the brain of vital nutrients. A lack of protein can lead to impaired memory, concentration, and critical thinking. The addition of excessive sugar only adds to the cognitive impairment. It's basically used to break down mental barriers. Physical exhaustion. Pushing people beyond the limits of their endurance through hard labor is one of the most common techniques used for this type of manipulation. When you're too tired to think clearly, you are often more vulnerable to suggestions and less able to resist other manipulation techniques. Lack of sleep. This only adds to the physical exhaustion caused by excessive work and poor diet. The human mind needs a sleep routine as much as the body does. Take away the routine and force the person to sleep/wake at random times, and it can break their mental barriers. Elimination of Time and Location. "Time" and "place" are two very important factors in human consciousness. Take away anything that could give an indication of time and location (dark, lightless environment in an unknown place), and you take away the foundation of what human consciousness is built on. Elimination of Sense of Identity. We all know who we are. I've been "me" since birth, and will continue to be until death. But the erasure of identity is possible—often by the removal of names in favor of a number or designation. With the mind so broken by fatigue, lack of sleep, and improper diet, it's possible to suppress one's identity. Repetition of Mantras. AA is a sort of cult, as is Nike, Apple, or Coca Cola. The use of mantras ("one day at a time" or "Just Do It") is a form of though reformation. Of course, these are just a few of the techniques used for psychological manipulation, thought reformation, or indoctrination. There are many more—this is a great link to check out. Pretty scary stuff, right? Imagine being a person who goes through that!