The gate on output from the nervous system is the stream of signals from within which alerts us to shortages and needs of the organism. Thus numbed internally, speed cuts the signals from the internal environment which indicate hunger or fatigue, not to mention more subtle signals involved in self-consciousness and self-control. (Hence its use as slimming aid and sleep preventer.)

This is diametrically opposed to the effects of cannabis, which opens the channels from within -- depending on the current state of satiety or otherwise, cannabis might trigger exaggerated hunger (the notorious howling munchies) or induce relaxation, or promote activity (if giggling inanely can be called activity!) according to what is indicated by the augmented flow from within.

Without these signals from within to tell us when our muscular activity has achieved its aim of balancing the system, whatever programme is instituted will run and run and run and run unchecked.

Whatever the speedfreak (you probably think this refers to someone else!) starts to do -- chattering or cleaning house, or dancing, or nose-picking, he or she will continue interminably, long after the time when any benefit might accrue from the activity. The signal from within which would normally terminate a program and trigger a change of activity fails to materialise. This is why speed-freaks (constituting most of the world's population who are hooked on tea/coffee/coca-cola, which is habitually substituted for real food, particularly by the mal-nourished) are so boring ... their (literal) lack of self-control is compensated for by their effect on other people, rather in the way that a car with no brakes is eventually brought to a halt by the things it bumps into or runs over or rubs up against.

Of course, lack of sensitivity to the internal environment builds up a backlog of regulatory activity which manifests itself as an oppressive come-down when eventually the speed is metabolised (broken down) and all the internal systems, which have drifted out of balance, send signals for attention simultaneously to an over-worked, under-nourished, still-numb brain.

Thus it can be seen that speed is a form of narcotic, differing from heroin or cocaine or alcohol in being more specific to signals from the internal environment than from the senses: like all narcotics, speed is addictive, requiring larger and larger doses to block the flow of demand for regulation for shorter and shorter periods.