magnesium, clonidine, anti-psychotics, and more benzos would definitely help to get to sleep, but i think its better to just time your dosage so the residual stimulation isn't much at all when it comes time to go to dreamland.
Having a benzo tolerance, and need for them to get sleep doesn't help either, not judging here at all, i need etizolam to sleep most nights. Just saying.
magnesium really helps me alot to get to sleep after using stimulating psychs/drugs.
Clonidine will drop your blood pressure, and take care of the adrenic affects of lsd that cause the stimulation in the first place.
Benzos imo are the least effective way to get to sleep after tripping.
And finally, GHB, if you have access to it, and can use it responsibly/safely, works very well for inducing sleep after tripping as well for me.
Anti-psychs will kill the trip, and i'd only use them as a last resort, or if you NEED the trip to stop for some reason, need for sleep being one of them, but definitely not the first choice for me, and personally i think i'd only use them if i was freaking out bigtime and needed to come down.