TRIGGER WARNING: TL;DR WALL OF TEXT WITH POWERLEVELING
It's still a little tentative at the moment, but I think I've made a big step toward solving my problems.
To recap some of the stuff I said previously, I seem to have delayed sleep phase disorder, and also a lot of symptoms resembling ADHD, OCD, generalized anxiety disorder and overall quite poor executive function. DSPD is often comorbid with ADHD and OCD. While I don't have panic attacks or wash my hands all day, it's basically a cluster of things that frequently make it exceedingly difficult and unpleasant to do anything useful.
None of this has been diagnosed, but I've been working on doing something about it. As I frequently tend to do, I was autistically over-preparing to make an appointment with a psychiatrist, where I expected to get prescriptions for modafinil and some sort of antidepressant. I ended up binge-reading a bunch of stuff and taking copious notes, because somehow that's easier for me than looking someone up and making a phone call (go ahead and start a halal thread for me).
I'd been taking 300 mcg melatonin two hours or so before my desired bedtime and trying bright light in the mornings, as is frequently recommended for DSPD, but it didn't seem to be doing anything. I'd typically wake up between 10 AM and 2 PM, my sleep schedule was erratic and sometimes totally chaotic, and I had problems with excessive daytime sleepiness and frequent headaches.
I started reading about
N-acetylcysteine (NAC) and how it's shown promise in treating a wide variety of disorders involving compulsive and impulsive behaviors (i.e. exactly the kinds of things I'm experiencing). NAC acts as a glutamate modulator and antioxidant; there's some evidence that people with OCD and related disorders have both glutamate abnormalities (correlated with increased impulsivity) and increased oxidative stress. The mechanism of action is (apparently) totally different from antidepressants. It seemed interesting and low risk, so I thought I'd try some. NAC is most often used as an antioxidant and mucolytic; it doesn't seem to have psychoactive effects in normal people.
I started taking the NAC and immediately felt a lot better and more focused, with fewer intrusive thoughts, impulsive behaviors, and much less overall discomfort. The degree of improvement in focus was comparable to Adderall, but without the stimulant effects. What was totally unexpected is that I also started spontaneously going to sleep earlier. Within 4 days I was waking up at 8 AM, and I didn't even mean to. I have
never, with any amount of effort, been able to advance my circadian rhythm like that. The melatonin now seems to be working as it should. I haven't seen anything at all about NAC affecting sleep (even after looking for it), so I was really surprised.
Things still aren't 100% under control, and I'm still having intermittent "relapses" of symptoms, so I think I'll have to play with the dosage and when and how I'm taking it. I'd been taking 1800 mg/day (for psychiatric use the dosage is usually around 1000-3000 mg/day), but I haven't found any good information on pharmacokinetics, etc. Everything went back to "normal" when I ran out.
One interesting thing to note is that I've always had very strong hypnagogic hallucinations and tend to dream immediately upon falling asleep, even if it's only for a second or two. This is common among narcoleptics, although I don't think I qualify for diagnosis. I also can't sit still without falling asleep, no matter how well rested I am. I've recently been using a seiza bench to meditate; typically the hypnagogic hallucinations start after 3-5 minutes, and I'll start nodding disruptively after about 10-12 minutes. This hasn't changed since starting the NAC. So something's likely still amiss, but it may not need treatment.
I'm ordinarily really suspicious of supplements, etc. Nootropics communities and other places where these sorts of things tend to be discussed and recommended are very often full of shit, and personal anecdotes from people who self-diagnose and self-medicate (myself included) are worth nothing. So I don't suggest you take my word for it, but at least for me it seems to have made a remarkable difference. It's a given that I'm a
special snowflake neurological outlier (for more reasons than what I've described here), so I wouldn't necessarily expect NAC to perform miracles for anyone else, but it might be worth trying in at least some cases. I also want to try choline and inositol, as they seem similarly promising.
. I have a sleep cycle that isn't regular... currently I'm sleeping during the day, and I'm awake from early afternoon till the sun is up. It will probably flip around again in a few weeks. Usually I sleep okay... it takes me forever to actually fall asleep, but once I'm out I'm gone. On days falling asleep is too hard, I take ambien and it knocks me out, but I don't take it regularly. 
