Which of the following is NOT typically a symptom of mental illness?

Extreme happiness is not typically classified as a symptom of mental illness in the same way that the other options are. Hallucinations, unusual thought patterns, and chronic sadness are common indicators associated with various mental health conditions. For example, hallucinations, which can involve seeing or hearing things that are not present, are often seen in disorders like schizophrenia. Unusual thought patterns might manifest in conditions such as bipolar disorder or delusional disorders, where individuals may experience significant disruptions in how they process information. Chronic sadness is a hallmark symptom of depression, where individuals experience prolonged periods of unhappiness and despair.

In contrast, extreme happiness is not inherently indicative of mental illness. While it can occur in the context of a mental health condition—such as the manic phase of bipolar disorder—the term itself can also describe a normal emotional experience. Therefore, it is clear why extreme happiness does not fit the pattern of symptoms typically associated with mental illnesses.