True about REM sleep-
**Core Concept**
REM (Rapid Eye Movement) sleep is a stage of sleep characterized by rapid eye movements, low muscle tone, and high brain activity. It plays a crucial role in memory consolidation, learning, and emotional regulation. During REM sleep, the brain's neurotransmitters and hormones are active, similar to those during wakefulness.
**Why the Correct Answer is Right**
REM sleep is associated with the release of neurotransmitters such as norepinephrine, serotonin, and acetylcholine, which are typically involved in attention and arousal. The brain's default mode network (DMN) is also active during REM sleep, allowing for the replaying and consolidation of memories. The pons, a part of the brainstem, regulates the transition between REM and non-REM sleep stages.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify a true characteristic of REM sleep. REM sleep is not solely characterized by increased heart rate and blood pressure.
**Option B:** This option is incorrect because it is a characteristic of non-REM sleep, not REM sleep. Non-REM sleep is associated with increased slow-wave activity and decreased brain activity.
**Option C:** This option is incorrect because it is a characteristic of both REM and non-REM sleep. Dreams can occur during both stages, but REM sleep is associated with more vivid and memorable dreams.
**Clinical Pearl / High-Yield Fact**
REM sleep deprivation can lead to impaired cognitive function, including attention and memory deficits. It is essential for medical professionals to be aware of the importance of adequate sleep in maintaining optimal cognitive function.
**Correct Answer:** C. Dreams occur during REM sleep.