NOC monkeys are pallid, asocial creatures confined to windowless buildings for 8-16 hours at a time. While some species are allowed to go home at sunset and remain on a fixed, somewhat daylike schedule, most data center sysadmins end up the victim of a rotating shift which sees the majority of their time either scheduled for the night shift or allocated to maintenance windows in the wee hours.
Most geeks revel in the idea of being up all night. However, what is originally a conscious choice to remain awake until dawn becomes a horrible curse when a career enforces the schedule. Long hours on the inside of concrete boxes wear down the morale and metabolism of NOClings; dirty air filters and a terrible diet consisting of energy drinks contributes to an unhealthy and sleep-deprived Morlock or dwarf-like creature contemptuous of human contact and driven to duty by spite alone.
The stereotypical picture of a sysadmin is that of an overweight, somewhat jovial bearded man with a strong tendency towards video games and incomprehensible mumbling about code. While this is an extreme (albeit somewhat common) case, often referred to as the Common Neckbeard, your more recent vintage tends towards scrawny or skinny guys with a bent towards healthier eating, nutritional supplements, martial arts, weight-lifting, or even vegetarianism.
Thus, the traditional drugs of choice for your average NOCling have shifted, resulting in additions to the three major drugs employed by night shift technicians.
The first and most widely-used drug of choice is caffeine. I have yet to meet a night shift technician with an antipathy towards the substance. While the usual induction involves soft drinks, more long term stays usually result the adoption of caffeine pills, energy drinks (such as Red Bull and Rockstar). Pathological cases tend to descend into swilling espresso in multiple shots or consumption of multiple tins of penguin mints a night.
Guarana is popular as a supplement, and is often added to energy drinks, five-hour energy shots, and pills. Soap and shower gel are also available for those who must scrub awareness into their very pores. For the less cleanly and more gaming-oriented nerds, Bawls are available sans the addition of caffeine. However, outside of energy drinks and Bawls, guarana is most often found paired with caffeine in a delicious synergistic cocktail.
Abuse of caffeine and/or guarana is common, resulting in a high resistance. Investment in espresso machines, ground caffeine, or even small sample bottles is possible, but yet another drug, this one rather more illegal, often surfaces. Thus, amphetamines come into play.
While not used by the majority of NOClings, amphetamines are popular among a certain subset of geeks seeking the ultimate edge in maintaining their razor sharp focus on the job. Many geeks find their introduction to speed in the arms of legitimate prescriptions for ADHD. For these unfortunates, medication usually remains their sole use of the drug. However, others supplement their regime, and still others begin to take it recreationally in parallel to caffeine and guarana.
On the theme of prescriptions, NOC work takes a heavy and stressful toll on the mental health of any geek. Even the most level-headed individuals may find themselves manifesting depression and/or anxiety disorders. Often, these are the result of grueling work, caffeine overdose, and a serial lack of sleep brought on by the latter. Eventually, many end up consulting psychiatrists and obtaining prescriptions for anti-anxiety meds and antidepressants. More unlucky sysadmins end up on tranquilizers in order to get to sleep in the morning. These medications are all addictive, even in the short term, resulting in yet another habit for the technician to kick after night shift ends.
Luckier souls end up with more "benevolent" means of sleep. In recent years, melatonin has become popular due to a relative lack of side-effects. Alcohol and NyQuil are also both quite common, resulting in a sideline in ugly liver problems, various overdose effects due to combination of downers, and an extremely poor quality of sleep. While melatonin is popular, it is also somewhat habit-forming, and scales very quickly in terms of resistance. Alcoholism is a more serious problem and a major contributor to overdoses - notably, alcohol is also highly synergistic with melatonin, leading to vivid dreams and increasing the impact of the supplement. NyQuil, on the other hand, simply doses you with DXM.
On a happier note, there are less harmful ways of maintaining focus and health. While fast food is often the usual cuisine of busier night techs, gas stations have begin stocking sandwiches, small fruit bowls, jerky, nuts, and other components of a healthy Morlock diet. When supplemented with Vitamin C or a good multivitamin, a healthy diet will often do far more for maintaining focus than abuse of caffeine or other drugs.
In conclusion, the healthiest means of dealing with long term assignment to night shift is to get off of night shift as soon as possible. This may require screaming at management, threats towards equipment or oneself, or even finding a new job.