The term duration refers to the length of time over which the subjective effects of a psychoactive compound manifest themselves. This can be further broken down into a total duration, an onset, a peak, an offset and after effects. Depending upon the substance consumed, each of these occur over different durations of time.
These are defined and listed below.
The total duration of a substance can be defined as the amount of time it takes for the substance's effects to completely wear off into sobriety, starting from when the substance was taken.
The onset can be defined as the period of time until the first noticeable changes in perception become apparent.
The "come up" can be defined as the period between the first noticeable changes in perception and the highest intensity of subjective effects. This is colloquially known as "coming up."
The peak can be defined as the height of intensity for the substance's effects.
The offset can be defined as the amount of time between feeling the full effects and coming down into sobriety. This is colloquially known as "coming down."
The after effects can be defined as any residual effects which may last after the experience itself. This is colloquially known as a "hangover" or an "afterglow" depending on the substance.