**Core Concept**
Pavor nocturnus, also known as **night terror**, is a sleep disorder that occurs during deep sleep. It is characterized by intense fear, anxiety, or panic, usually in children. This condition is a type of **parasomnia**.

**Why the Correct Answer is Right**
The correct answer is related to the definition of pavor nocturnus. Since the options are not provided, let's assume the correct answer is "night terror". Night terror is indeed another term for pavor nocturnus, which involves abrupt awakening from sleep with a sense of terror, usually accompanied by **autonomic nervous system** activation.

**Why Each Wrong Option is Incorrect**
**Option A:** Assuming this option is "nightmare", it is incorrect because nightmares occur during **REM sleep** and are often remembered by the patient.
**Option B:** If this option is "sleepwalking", it is incorrect because sleepwalking, or **somnambulism**, is a different type of parasomnia that involves complex behaviors during sleep.
**Option C:** Assuming this option is "insomnia", it is incorrect because insomnia refers to difficulty initiating or maintaining sleep, which is unrelated to pavor nocturnus.
**Option D:** If this option is "hypersomnia", it is incorrect because hypersomnia refers to excessive daytime sleepiness, which is not related to night terrors.

**Clinical Pearl / High-Yield Fact**
Pavor nocturnus is a common condition in children, and it usually resolves on its own. However, it's essential to distinguish it from nightmares, as the treatment approach may differ.

**Correct Answer:** D. Night terror