One reason I like modafinil is that it enhances dopamine release, but it binds to your dopamine receptors differently than addictive substances like cocaine and amphetamines do, which may be part of the reason modafinil shares many of the benefits of other stimulants but doesn’t cause addiction or withdrawal symptoms.   It does increase focus, problem-solving abilities, and wakefulness, but it is not in the same class of drugs as Adderall, and it is not a classical stimulant. Modafinil is off of patent, so you can get it generically, or order it from India. It’s a prescription drug, so you need to talk to a physician.
On the other hand, Phillips said, Provigil's effects "have attenuated over time. The body is an amazing adjusting machine, and there's no upside that I've been able to see to just taking more." A few years ago Phillips tired of poker and started playing competitive Scrabble. He was good, but not that good. He was older than many of his rivals and he needed to undertake a lot of rote memorisation, which didn't come as easily as it once had. "I stopped short of memorising the entire dictionary, and to be really good you have to get up to eight- and nine-letter words," he told me. "But I did learn every word up to five letters, plus maybe 10,000 seven- and eight-letter words." Provigil, he said, helped with the memorisation process but, "it's not going to make you smarter. It's going to make you better able to use the tools you have for a sustained period."
There are a number of treatments for the last. I already use melatonin. I sort of have light therapy from a full-spectrum fluorescent desk lamp. But I get very little sunlight; the surprising thing would be if I didn’t have a vitamin D deficiency. And vitamin D deficiencies have been linked with all sorts of interesting things like near-sightedness, with time outdoors inversely correlating with myopia and not reading or near-work time. (It has been claimed that caffeine interferes with vitamin D absorption and so people like me especially need to take vitamin D, on top of the deficits caused by our vampiric habits, but I don’t think this is true35.) Unfortunately, there’s not very good evidence that vitamin D supplementation helps with mood/SAD/depression: there’s ~6 small RCTs with some findings of benefits, with their respective meta-analysis turning in a positive but currently non-statistically-significant result. Better confirmed is reducing all-cause mortality in elderly people (see, in order of increasing comprehensiveness: Evidence Syntheses 2013, Chung et al 2009, Autier & Gandini 2007, Bolland et al 2014).
When you start taking legit nootropics, you get to leave all of that behind you. You may never achieve perfect concentration (most of us never will), but you should find you are able to concentrate on the task at hand for much longer than you do now. You will end up taking fewer breaks, and you might start finishing up your work on time each day again—or even early!
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. Nonetheless, the international sales of cognition-enhancing supplements exceeded US$1 billion in 2015 when global demand for these compounds grew.