Psychoneurosis, also known as neurosis, is a mental disorder that causes a sense of distress and a deficit in functioning. Neuroses are characterized by anxiety, depression, or other feelings of unhappiness or distress that are out of proportion to the circumstances of a person’s life.

An influential view held by the psychoanalytic tradition is that neuroses arise from intrapsychic conflict (conflict between different drives, impulses, and motives held within various components of the mind). Central to psychoanalytic theory, which was founded by Austrian neurologist Sigmund Freud, is the postulated existence of an unconscious part of the mind that, among other functions, acts as a repository for repressed thoughts, feelings, and memories that are disturbing or otherwise unacceptable to the conscious mind. These repressed mental contents are typically sexual or aggressive urges or painful memories of an emotional loss or an unsatisfied longing dating from childhood. Anxiety arises when these unacceptable and repressed drives threaten to enter consciousness; prompted by anxiety, the conscious part of the mind (the ego) tries to deflect the emergence into consciousness of the repressed mental contents through the use of defense mechanisms such as repression, denial, or reaction formation.