I worked 12hr night shifts for 10 years, in that time I was a heavy smoker, a habitual user of potent stimulants, and mixed up different ways of gettin ginto and out of bed downing 4 redbulls every night to wake up and pills to get me back to sleep.

The human body is kinda dumb in some respects. Every chemical process is somewhat connected to other processes making it difficult to target a single thing. Like, you can dose up on a GABA agonist like benzos to get to sleep but it will also affect other systems such as memory retention and recall, digestion, motor function etc. Same goes for SSRIs, pain killers etc.

Sleep itself is a fairly stable function but is easily disrupted by our modern activity and habits. You.can accidentally prevent sleep through many means. Nicotine, theobromine, sugar, alcohol, substance withdrawal, use of bright screens, lack of physical activity, and of course the simple one, caffiene. On the flip side, artificially inducing sleep will make sleeping dependant on the substance to pass out in the future. I've tried opiates, cannabinoids, dissociatives, benzos, herbal remedies, antihistamines, and my absolute favourite, stimulant exhaustion. No matter what you take, the body gets used to it quickly and will need and want more the next time.

After giving up benzos and nicotine cold turkey while still on nights, I learned quick to deal with the usual sleep deprivation hallucinations, the memory problems, the physical debilitation. But it passed in mere weeks. A great trick to calm the mind is to picture an object, focus on the whole object, like a bicycle. Zoom into a smaller area of the object, a wheel. Inspect it. Zoom into the tyres, visualise the texture. Zoom into the air valve. Repeat this and the mind will calm and you will sleep with less noise.

You are right about the sun resetting the body clock. Night shifters have higher instances of diabetes, in part because they eat irregularly. When the sun comes up they get hungry. If you pull all nighters, you disrupt your body clock.

Interestingly, even some minor things can affect sleep. Taking vitamin d before sleep can disrupt it, whereas taking it every morning can help stabilise your sleep.

Detoxing is a wonderful thing. Trust me, after taking over 50 different psychoactives, mostly stimulants, sleep is not something that you magically fix with adding more and more substances, it's the opposite.