system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How Are Sleep Cycles Regulated In The Brain

As someone living with narcolepsy, I know a lot about managing my sleep. Going to bed at the same time, waking up at the same time, consistency, etc. there are a ton of things you can do to improve your quantity and quality of sleep.

That said, I know nearly nothing about *why* a lot of these things are required. To me, for example, it makes no sense that one would feel more rested if they woke up in the morning, versus the night, and yet that's merely one stipulation to restful sleep; there are a lot more that seem like they don't make sense.

What I would like to learn from this thread is what chemicals are used, how/why they are produced and consumed, and what can be done to "cure" narcolepsy (given said information about chemicals and whatnot).
gpt
There are a lot of parts of the brain involved in sleep and arousal. 

One part is the eyes themselves. There are specialized cells called ipRGCs (intrinsically photoreceptive retinal ganglion cells) that are not involved in vision, but send signals that it’s daytime and you should be awake. They do this by reducing the amount of melatonin that is released. The ipRGCs send signals to a part of the brain called the SCN (suprachiasmatic nucleus) that regulates the pineal gland, which is where melatonin is produced and released. If you try to wake up at night then the ipRGCs don’t send the signal to the SCN and so melatonin is not suppressed.