**Core Concept:** Post-traumatic stress disorder (PTSD) is a psychiatric disorder that can develop in individuals who have experienced or witnessed a traumatic event. Symptoms include intrusive memories, avoidance behaviors, hyperarousal, and re-experiencing the trauma. Night sweats and terrified episodes can be a part of the hyperarousal symptom cluster.

**Why the Correct Answer is Right:** The correct answer is PTSD because a child experiencing night sweats and terrified episodes without remembering the event is a common presentation of the disorder. In PTSD, the brain's autonomic nervous system is hyperactive, leading to symptoms like excessive sweating and emotional distress during nightmares or flashbacks.

**Why Each Wrong Option is Incorrect:**
A. Mental exhaustion: While fatigue can be a symptom, the question focuses on night sweats and terrified episodes, which are specific to PTSD.
B. Primary sleep disorder: Night terrors are a type of primary sleep disorder, typically affecting children and characterized by sudden awakenings with fear and autonomic symptoms. However, the child in the question remembers the episode and is not suffering from true night terrors.
C. Psychomotor retardation: This is a symptom of depression, not PTSD. The child is terrified and experiencing autonomic symptoms, not showing psychomotor retardation.
D. Seizures: Seizures are characterized by generalized convulsions rather than specific autonomic symptoms and memory recall.

**Core Concept (repeated):** PTSD is a psychiatric disorder triggered by traumatic experiences, leading to intrusive memories, avoidance behaviors, hyperarousal, and re-experiencing the trauma.

**Why Each Wrong Option is Incorrect (repeated):**
A. Mental exhaustion: While fatigue can be a symptom, night terrors are a specific sleep disorder.
B. Primary sleep disorder: Night terrors are a type of primary sleep disorder, not PTSD.
C. Psychomotor retardation: This is a symptom of depression, not PTSD.
D. Seizures: Seizures are characterized by generalized convulsions, not the specific autonomic symptoms and memory recall observed in PTSD.

**Clinical Pearl:** Recognizing the core symptoms of PTSD, such as autonomic symptoms and intrusive memories, is crucial for accurate diagnosis and appropriate treatment. In children, night terrors may present similarly, but they are characterized by sudden awakenings with autonomic symptoms and autonomic responses, rather than intrusive memories and flashbacks seen in PTSD.