I think nicotine causes release of acetylcholine and acetylcholine is what the brain releases when REM sleep starts so maybe the nicotine could make the early sleep stages of sleep way more active before you get down to the deeper levels. Just a guess but I think it makes a lot of sense nicotine affects the brain just before and during sleep. I also think going to sleep when you have been awake an extra long time can contribute to the paralysis & hallucinations. Would be cool to get some brain geeks to weigh in on this.
Acetylcholine is a chemical that mainly stimulates muscles, and too much of it can be deadly. In fact, nerve gas shuts down the enzyme in your body that breaks down acetylcholine, which is why it's so sadistically dangerous. Generally speaking, nightmares arise from your body being uncomfortable during sleep. When I used to write horror stories, I would induce nightmares... by eating salsa before bed, or wearing socks when I don't normally (I'd also take vitamin B6, which is said to make dreams much more vivid). Something that upsets your system in some way while you sleep can induce nightmares or crazy dreams. Nicotine is a stimulant, so I'd say it simply upsets your system (this could be due in part to the acetylcholine release) and causes the weird dreams. Personally I wouldn't read too much into it; we don't know very much about dreams, or what causes them or why. We simply have statistics. As they say, "dreams are of no interest in modern psychology"!
Thanks LaraPaw, interesting read. That really sounds like what I have been experiencing! Especially the auditory, visual hallucinations and the feeling of suffocation accompanied with the sleep paralysis. I'm not sure what the effect of nicotine is on them, but I have had them a bit more in the past few years when I've been vaping. Just glad it isn't very threatening.
I've had sleep paralysis a few times. It's not fun, and is closer to night terrors than actual nightmares. There's an old painting called "The Nightmare" by Fuseli that effectively shows what is often felt during it (suffocating feeling, which leads to believing there's a demon on your chest). It's also very common to see bright lights outside your window, or shadowy figures moving around your room. Actually, it's the #1 explanation for most of the supposed alien abduction cases!
They say it happens to everyone at least once in their life, but some people are more prone to it than others. I've had it 3 or 4 times now, and I can usually feel it coming on now and snap myself awake before it happens.
We don't know what causes it, we just know it comes from your brain "waking up" after it's shut down your muscles (otherwise you'd act out your dreams!). It's essentially dreaming while you're awake, and while it's scary, it doesn't hurt you in any way. If you want to avoid it, the best way to try is to have a regular/rigid sleep schedule.