A nurse is caring for a client who has narcolepsy (NT1) with cataplexy. The nurse should identify that this condition is caused by a lack of which of the following hormones?
Hypocretin
Melatonin
Estrogen
Insulin
The Correct Answer is A
A. Hypocretin (also called orexin) is a neuropeptide produced in the hypothalamus that plays a critical role in regulating wakefulness, arousal, and REM sleep. In narcolepsy type 1 (NT1), the body’s immune system often mistakenly attacks and destroys the hypocretin-producing neurons. The resulting deficiency leads to the hallmark symptoms of NT1: excessive daytime sleepiness, sudden onset of REM sleep, and cataplexy—brief episodes of muscle weakness triggered by strong emotions such as laughter, anger, or surprise. Recognizing hypocretin deficiency as the underlying cause helps the nurse understand why pharmacologic interventions (such as stimulants, sodium oxybate, or wake-promoting agents) and behavioral strategies (scheduled naps, sleep hygiene) are essential in management.
B. Melatonin is a hormone secreted by the pineal gland that regulates the body’s circadian rhythm and promotes sleep onset at night. While melatonin influences the timing of sleep, a deficiency does not cause narcolepsy or cataplexy, and supplements typically do not improve the daytime sleepiness characteristic of NT1.
C. Estrogen is a sex hormone that regulates reproductive functions and secondary sexual characteristics. It does not play a role in the neurochemical mechanisms that control wakefulness or muscle tone and is unrelated to narcolepsy.
D. Insulin is a pancreatic hormone essential for glucose metabolism. While hypoglycemia can cause fatigue or sleepiness, insulin deficiency or excess is not implicated in the pathophysiology of narcolepsy, and insulin therapy does not affect cataplexy or REM sleep regulation.
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Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
A. Older adults experience a decrease in stage 4 sleep, which is the deepest, slow-wave sleep responsible for physical restoration, tissue repair, and immune system support. The reduction in stage 4 contributes to lighter sleep, less restorative rest, and increased susceptibility to awakenings during the night.
B. Stage 3 sleep, another component of deep, slow-wave non-REM sleep, also decreases with age. This decline reduces the total amount of restorative sleep, which can lead to daytime fatigue, difficulty concentrating, and increased nighttime awakenings.
C. Stage 1 sleep, the lightest stage of non-REM sleep, does not significantly decrease with age. Older adults continue to enter stage 1 sleep as a normal part of the sleep cycle. However, the proportion of light sleep relative to deep sleep increases, making the overall sleep more fragmented and easier to disrupt.
D. Older adults spend more time in stage 2 sleep, which is a lighter stage of non-REM sleep characterized by sleep spindles and slower brain activity. While stage 2 is important for memory consolidation and some restorative processes, it is easier to awaken from than stages 3 and 4. The increased proportion of stage 2 sleep contributes to frequent nighttime awakenings, lighter sleep, and shorter total sleep time, which are common complaints among older adults.
Correct Answer is B
Explanation
A. Ghrelin is a hormone produced by the stomach that stimulates appetite. Higher ghrelin levels are associated with increased hunger and caloric intake. Sleep deprivation increases ghrelin, which can contribute to weight gain. Therefore, increasing sleep would decrease ghrelin, not increase it, and help reduce weight gain.
B. Leptin is a hormone secreted by adipose (fat) tissue that signals satiety to the brain and suppresses appetite. Adequate sleep helps maintain normal leptin levels, which can reduce overeating and help prevent weight gain. This makes increased leptin production a beneficial effect of improving sleep for clients with insomnia and recent weight gain.
C. Hypocretin (also called orexin) is a neuropeptide that promotes wakefulness and alertness. While excessive wakefulness can contribute to sleep problems, decreasing hypocretin is not a primary mechanism for controlling weight gain. Disrupting hypocretin can actually cause sleepiness and may have other metabolic consequences.
D. Melatonin is a hormone produced by the pineal gland that regulates sleep-wake cycles. Sleep increases melatonin secretion rather than decreasing it. Reduced melatonin is associated with insomnia and circadian rhythm disruption. Therefore, decreased melatonin would not be beneficial for sleep or weight control.
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