In Chinese philosophy, the concepts of yin and yang are two opposing forces that also complement each other, creating a harmonious balance. This balance is considered as the true “natural” state of everything from a person's mental health to the actual workings of the planet. It is a mistake to see yin and yang as representation of “good” and “evil,” with “night” and “day” being more appropriate, albeit highly metaphorical comparisons. The idea behind this philosophy is that in all things is a natural balance between two sets of characteristics, with one set being yin and the other being yang. It is interesting to note how these comparisons can be applied to the field of mental health, particularly when studying human personalities. Take note that by no means is any of the following to be considered concrete, scientific doctrine. However, it does present an alternative avenue to the study of the various personality and psychological traits that make up human beings. Used in the context psychology, students are taught that a person's yin aspects represent the feminine side of a psyche. However, yin also corresponds to order, law, and self-control, with an excess of it resulting in stagnation and a lack of emotion. In terms of mental health, this lack of emotion can display itself in a variety of ways, both on its own and in conjunction with other mental disorders.

For example, an excessive focus on what are considered a person's yin traits, when combined with status anxiety, can result in a person showing excess duplicity and ruthlessness in his attempts to retain or improve his perceived station in life. In some ways, this can also be misinterpreted as social anxiety, as some have noted that people with a great focus on their yin aspects tend to view other people disdainfully, failing to understand how others can view emotions to be of any importance. According to some older texts on the yin and yang, psychological impotence can also result from an excess in a person's mental yin, emerging from the complete and total suppression of all emotions – including the sex drive.

By comparison, yang is said to represent the masculine side of the mind. It corresponds to creativity, instinct, and impulsiveness, though excessive development can result in a dangerous recklessness and clinical insanity. Seen through the lens of mental health terms, this can result in some of the more common psychological disorders that people are aware of, as the yang aspects of a person are closely tied with the outer mental facade.

Examples of effects of over-developed yang aspects can include anxiety disorders, separation anxiety, performance anxiety, depression, dissociative identity disorder, obsessive-compulsive disorder, and manic-depressive disorder. Mental health that is yang-dominated can often be seen as overtly dangerous, with individuals being more interested in the expression of their baser desires, which can manifest as a desire to do violence in certain individuals. Due to the outward nature of a yang-dominated psyche, the manifestations of excess are significantly easier to detect than in yin-dominated ones, which tend to exhibit more subdued, perhaps even hidden, “deviancies” from the cultural and social norm.

A balance between yin and yang, theoretically, is present in most of the population. Yin and yang are cyclical forces, which can conveniently explain the inherent contradictions of the typical human being. According to the theories put forth by modern mental health experts who have merged Western and Oriental schools of thought, imbalances in either yin or yang can possibly lead to mental disorders. Theoretically, it is impossible for one side to be of such complete dominance that the other side is no longer present in a psyche. According to traditional concepts, even if one is shown to be dominant over the other, this is merely a disruption in the balance and not a complete absence of the side --- showing that there is a continuous interplay between the yin and yang. For example, even the clinically insane occasionally exhibit signs of concern for their own well-being. This is taken as a sign that the yin still has influence over the person's actions, even in those who are mentally ill. On the other hand, even the most calculating and logical thinkers feel emotions, even without allowing themselves to be swayed by them. The concept of emotions, as well as the ability to recognize them, is taken as a yang trait.

Indeed, the yin and yang of the human mind and personality makes an excellent subject for research. By understanding the duality in all things, which includes human thought and behavior, we would be able to catch a glimpse about the remarkable interplay of motive, emotions, and actions in people who all represent the reality of yin and yang.