Here's something almost unbelievable I've heard:
Heroin addicts can have intense setting based tolerance, they can be used to taking a certain (high) dose the way they are used to in the (sort of) situation or even also place they are used to and it works like a charm.
But apparently it's quite possible for such a person if they would take the same dose in a situation that is totally different, unexpected and which they are not used to they might very well die from an overdose.
It seems your mind can initiate a sort of defense mechanism for that which is expected to follow. Similar to a flashback with psychosomatic consequences even the whole anticipation of taking that hit will get them in the mode to be able to handle it.
With things like GHB and LSD and MDMA and many other drugs it's possible to feel the effects much quicker once you have used it more often because everything about the start of the experience reminds you so much of the effects that they can already start to manifest themselves. It's like a cousin of placebo but not quite the same.
With certain substituted methcathinones I excrete metabolites or the compound itself in my sweat, the smell which is at the same time a bit nasty as well as nice to me ... I associate with the highly euphoric effects so much that having a shirt near me that I wore a day earlier when high on the stuff totally brings back the effects for a pretty big part. The smell of 4-FMC for instance is somewhere between that of very sweet cat pee and a floral scent. Mind you though, that the euphoria is so deeply associated with it that I cannot label the smell as foul even though it probably is to someone who has never used the drug.
My own sweat may also play a role, someone who has the exact same phenomena may find my sweat a little revolting because it doesn't remind him of
himself being high on the stuff. Now I'm just hypothesizing, don't even know if there are other people who hop on their own bodily scents.
Erm.... ok it's a bit strange but that's just the way it is.
Music is also a known trigger besides smells for this sort of reliving memories. Positive flashbacks almost, that are hardwired by intense reactions - very pleasurable effects or intense emotions for instance. Significant experience, to conclude.
