In August 2011, after winning the spaced repetition contest and finishing up the Adderall double-blind testing, I decided the time was right to try nicotine again. I had since learned that e-cigarettes use nicotine dissolved in water, and that nicotine-water was a vastly cheaper source of nicotine than either gum or patches. So I ordered 250ml of water at 12mg/ml (total cost: $18.20). A cigarette apparently delivers around 1mg of nicotine, so half a ml would be a solid dose of nicotine, making that ~500 doses. Plenty to experiment with. The question is, besides the stimulant effect, nicotine also causes habit formation; what habits should I reinforce with nicotine? Exercise, and spaced repetition seem like 2 good targets.
Caffeine (; FDA adverse events) is of course the most famous stimulant around. But consuming 200mg or more a day, I have discovered the downside: it is addictive and has a nasty withdrawal - headaches, decreased motivation, apathy, and general unhappiness. (It’s a little amusing to read academic descriptions of caffeine addiction9; if caffeine were a new drug, I wonder what Schedule it would be in and if people might be even more leery of it than modafinil.) Further, in some ways, aside from the ubiquitous placebo effect, caffeine combines a mix of weak performance benefits (Lorist & Snel 2008, Nehlig 2010) with some possible decrements, anecdotally and scientifically:

Directions — as a dietary supplement take 2 veggie capsules once a day . For best results take 20-30 min before a meal with an 8oz. Glass of water or as directed by your healthcare professional. As a dietary supplement take two (2) veggie capsules once a day. For best results take 20-30 minutes before a meal with an 8oz. glass of water or as directed by your healthcare professional. — Suggested Use: As a dietary supplement, adults take one (1) capsule per day. Do not exceed 2 capsules per day. —
If Brainfood was important to you, help honor our work in your own life. Try cooking a new recipe and sharing it with a neighbor. Extend grace to those learning new skills. Volunteer somewhere that makes you smile and also respects your time. Create spaces where young people from diverse backgrounds are valued and seen. And always, always make sure to share your snacks.
Another promising "smart pill" is phosphatidylserine, or PS, a natural substance that helps cell walls stay pliable and is thought to boost the effectiveness of neurotransmitters, which relay brain signals. In a May 1991 study published in Neurology, neuroscientist Thomas Crook found that patients with age-associated memory impairment improved their scores on key performance tests after 12 weeks on PS. Yet more research is needed before doctors can know that the supplement is safe and effective.
It is not because of the few thousand francs which would have to be spent to put a roof [!] over the third-class carriages or to upholster the third-class seats that some company or other has open carriages with wooden benches. What the company is trying to do is to prevent the passengers who can pay the second class fare from traveling third class; it hits the poor, not because it wants to hurt them, but to frighten the rich. And it is again for the same reason that the companies, having proved almost cruel to the third-class passengers and mean to the second-class ones, become lavish in dealing with first-class passengers. Having refused the poor what is necessary, they give the rich what is superfluous.
Blueberries and blackberries are at the top of the list of brain-boosting foods because they are exceptionally rich in chemicals called anthocyanins, which are among the most potent antioxidants. "But the real message here is that a diet rich in fruits and vegetables of all kinds does more than keep your heart healthy," says Tufts University neurobiologist James Joseph. It's healthy food for thought.

More photos from this reportage are featured in Quartz’s new book The Objects that Power the Global Economy. You may not have seen these objects before, but they’ve already changed the way you live. Each chapter examines an object that is driving radical change in the global economy. This is from the chapter on the drug modafinil, which explores modifying the mind for a more productive life. 
Clarke and Sokoloff (1998) remarked that although [a] common view equates concentrated mental effort with mental work…there appears to be no increased energy utilization by the brain during such processes (p. 664), and …the areas that participate in the processes of such reasoning represent too small a fraction of the brain for changes in their functional and metabolic activities to be reflected in the energy metabolism of the brain… (p. 675).
After I ran out of creatine, I noticed the increased difficulty, and resolved to buy it again at some point; many months later, there was a Smart Powders sale so bought it in my batch order, $12 for 1000g. As before, it made Taekwondo classes a bit easier. I paid closer attention this second time around and noticed that as one would expect, it only helped with muscular fatigue and did nothing for my aerobic issues. (I hate aerobic exercise, so it’s always been a weak point.) I eventually capped it as part of a sulbutiamine-DMAE-creatine-theanine mix. This ran out 1 May 2013. In March 2014, I spent $19 for 1kg of micronized creatine monohydrate to resume creatine use and also to use it as a placebo in a honey-sleep experiment testing Seth Roberts’s claim that a few grams of honey before bedtime would improve sleep quality: my usual flour placebo being unusable because the mechanism might be through simple sugars, which flour would digest into. (I did not do the experiment: it was going to be a fair amount of messy work capping the honey and creatine, and I didn’t believe Roberts’s claims for a second - my only reason to do it would be to prove the claim wrong but he’d just ignore me and no one else cares.) I didn’t try measuring out exact doses but just put a spoonful in my tea each morning (creatine is tasteless). The 1kg lasted from 25 March to 18 September or 178 days, so ~5.6g & $0.11 per day.
The NIDA research study focused on 10 healthy male participants. The men were subjected to two rounds of PET brain scans after consuming either Provigil (200 mg or 400 mg) or a placebo. The scans demonstrated that the Provigil users had an increase in the amount of dopamine in the brain. Dopamine is a key neurological messenger in the brain’s reward system. Cocaine and methamphetamine have a similar effect on the brain, but they are more potent and faster-acting than Provigil. As cocaine and amphetamines are addiction-forming, the reasoning here is that Provigil may also be addictive.
The use of cognition-enhancing drugs by healthy individuals in the absence of a medical indication spans numerous controversial issues, including the ethics and fairness of their use, concerns over adverse effects, and the diversion of prescription drugs for nonmedical uses, among others.[1][2] Nonetheless, the international sales of cognition-enhancing supplements exceeded US$1 billion in 2015 when global demand for these compounds grew.[3]