**Question:** Which of the following is a classical symptom of depression:-

A. Anhedonia (inability to experience pleasure)
B. Fatigue
C. Insomnia
D. Hypersomnia

**Core Concept:** Depression is a mood disorder characterized by a persistent feeling of sadness, loss of interest, and altered mood regulation. It is a complex disorder influenced by genetic, environmental, and psychological factors. The classical symptoms of depression are categorized into three groups: affective symptoms, cognitive symptoms, and somatic symptoms.

**Why the Correct Answer is Right:** Anhedonia (A) is a key symptom of depression, as it reflects a diminished ability to experience pleasure or enjoyment in activities that were previously enjoyable. This is one of the core cognitive symptoms of major depressive disorder (MDD), and is a significant indicator of a potential MDD diagnosis.

**Why Each Wrong Option is Incorrect:**

B. Fatigue (B) is a common symptom of depression, but it may also occur in other conditions like fatigue in primary care. It is not specific to depression, making it less reliable as a standalone symptom.

C. Insomnia (C) is a common somatic symptom in depression, but hypersomnia (D) refers to excessive sleep or increased sleep duration, which is also a common symptom in depression. Both insomnia and hypersomnia can be found in patients with depression, making them less reliable as standalone symptoms.

**Why Each Wrong Option is Incorrect:**

D. Hypersomnia (D) is an incorrect answer as it represents excessive sleep or increased sleep duration, which is also a common symptom in depression. Both insomnia (C) and hypersomnia (D) can be found in patients with depression, making them less reliable as standalone symptoms.

**Clinical Pearl:** To diagnose depression, it is essential to consider the combination of symptoms. A patient with two or more symptoms from the following groups: mood symptoms (anhedonia, depressed mood), cognitive symptoms (fatigue, low energy, difficulty concentrating), and somatic symptoms (insomnia, hypersomnia, gastrointestinal issues, weight loss/gain, etc.) is more likely to suffer from depression. This combination of symptoms is evaluated in the DSM-5 diagnostic criteria for Major Depressive Disorder.