If the patient has a problem with the pineal gland, melatonin substance would the nurse monitor.
What is melatonin? 
- melatonin has long been linked to the regulation of the sleep-wake cycle in animals, where it is primarily known as a hormone secreted at night by the pineal gland in the brain.
- Brain releases the hormone melatonin in reaction to darkness. 
- It aids in sleep and the timing of your circadian rhythms. 
- Light exposure at night can prevent the generation of melatonin.
- Avoid operating heavy machinery or driving within five hours of taking melatonin because it may make you drowsy during the day. 
- Additionally, melatonin supplements may interfere with a number of pharmaceuticals, such as antiplatelet and anticoagulant medications.
- A hormone called melatonin regulates your circadian cycle. 
- When you are exposed to darkness, your body survives.
Learn more about melatonin here:
https://brainly.com/question/14602834
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