Early morning awakening and reduced latency of REM sleep is suggestive of –
**Core Concept**
Early morning awakening and reduced latency of REM sleep are characteristic features of a specific sleep disorder. These symptoms are often associated with an imbalance in the normal sleep-wake cycle and brain chemistry. The sleep-wake cycle is regulated by the suprachiasmatic nucleus (SCN) and the sleep-promoting neurons in the brain.
**Why the Correct Answer is Right**
The correct answer is associated with an increased activity of the neurotransmitter norepinephrine, which suppresses the sleep-promoting neurons in the brain. This leads to an earlier transition from non-rapid eye movement (NREM) sleep to REM sleep, resulting in reduced latency of REM sleep. Additionally, the increased activity of norepinephrine disrupts the normal sleep-wake cycle, leading to early morning awakening.
**Why Each Wrong Option is Incorrect**
* **Option A:** This is incorrect because it is associated with increased activity of serotonin, which promotes relaxation and sleep. It is not typically associated with early morning awakening and reduced latency of REM sleep.
* **Option B:** This is incorrect because it is associated with increased activity of acetylcholine, which is involved in the regulation of REM sleep. However, it is not typically associated with early morning awakening.
* **Option C:** This is incorrect because it is associated with decreased activity of the SCN, which regulates the sleep-wake cycle. However, it is not typically associated with reduced latency of REM sleep.
**Clinical Pearl / High-Yield Fact**
The key to differentiating between various sleep disorders is to identify the specific symptoms and patterns of sleep disruption. For example, early morning awakening and reduced latency of REM sleep are characteristic of depression, whereas insomnia is often associated with difficulty falling asleep and fragmented sleep.
**Correct Answer: C. Depression.**