let's just plunge right in, shall we.
A person has a longer perception of time with sobriety, a shorter perspective of time when they practice using drugs (alcohol is unquestionably a drug) or are in constant periods of highly stressful or exciting sitauations for an extended period of time. As this is easily accomplished with drugs, the rest of the focus of this writeup will use the drug user to compare to a healthy sober person. Naw!, I don't have first-hand experience or anything. Of course not.
By perspective of time I mean that a sober well adjusted individual would generally think in terms of days, or a whole week, including the past couple of days, the present, and a couple of days into the future. This way periods of excitement and stress will balance out with the periods of inactivity or boredom. The levels of neurotransmitters and thus general well being and happiness will reach a constant healthy level. Compare this to the chronic drug and alcohol user who experiences extremely high rises in brain levels and activity followed by extreme drops. The brain compensates for this by narrowing its perception down to one day or shorter. In order to operate at that level the brain must let some steam off so to speak. The drug user thinks in terms of hours, what he/she is going to be experiencing in their heads that day. Tomorrow is unimportant; it's all about what you can score today. The brain becomes used to the quick pace of rises and drops and adjust itself accordingly but not without a sacrifice.
This can negatively affect memory, forethought and happiness. When you have a bad day while experiencing this limited perspective, the whole world is crumbling around you. Similarly, it's difficult to summon patience and attain the satisfaction of continuing a long work that can last months or even years. It is hard for someone in this state to project their satisfaction and happiness that far into the future. In short, drug users live more keenly in the now than does the rest of the population. This does allow for a life of extremes and thrilling intensity, but is duly taxing on the mind body and spirit. It also describes an addiction that isn't based on a physical, but rather mental withdrawal. It takes a period of anywhere from weeks to years for the brain to extend or detract its perspective of time. As well as the physical withdrawal, a susbstance can cause this mental withdrawal. The user experiences a need for that stimulation just to satisfy the addiction of the mind. It explains how some people are just addicted to substances in general, and don't become physically addicted to any single drug.
That this is happening to them is not fully realized until they stop using substances in general. The brain slowly extends its perception of time again. The user finds that they can stay away from the need for constant stimulation because he/she consciously registers all of the stimulation he/she receives in a week, not a day. It starts to feel all right to slow down. The ability to have the qualities of patience, diligence, peace and contentment slowly return with time.