These days, young, ambitious professionals prefer prescription stimulants—including methylphenidate (usually sold as Ritalin) and Adderall—that are designed to treat people with attention deficit hyperactivity disorder (ADHD) and are more common and more acceptable than cocaine or nicotine (although there is a black market for these pills). ADHD makes people more likely to lose their focus on tasks and to feel restless and impulsive. Diagnoses of the disorder have been rising dramatically over the past few decades—and not just in kids: In 2012, about 16 million Adderall prescriptions were written for adults between the ages of 20 and 39, according to a report in the New York Times. Both methylphenidate and Adderall can improve sustained attention and concentration, says Barbara Sahakian, professor of clinical neuropsychology at the University of Cambridge and author of the 2013 book Bad Moves: How Decision Making Goes Wrong, and the Ethics of Smart Drugs. But the drugs do have side effects, including insomnia, lack of appetite, mood swings, and—in extreme cases—hallucinations, especially when taken in amounts the exceed standard doses. Take a look at these 10 foods that help you focus.
Siberian Ginseng: Also known as Eleutherococcus senticosus, this herb is native to Russia, China, Japan and other areas of east Asia.  There is not a lot of western research backing Siberian Ginseng as a nootropic yet, but the supplement has been used in traditional medicine in the Far East for quite some time.  Plenty of anecdotal evidence backs it up as an excellent memory and attention enhancer.
Consider something as simple as a phone call. You hear the phone ring – your auditory capacity kicks in. Next, you decide whether to answer – decision-making comes into play. You reach for the phone – calling your motor skills to work. You answer – using your voice – all controlled by your brain, all done in mere moments, without conscious thought. Your brain works non-stop, consuming mental energy and physical resources.
Microdosing with Iboga: Native to the rainforests in Central Africa, Iboga is an evergreen shrub, with high concentrations found in the root bark. It has a rich history amongst practitioners in the indigenous Bwiti religion in Africa and has recently found its way into Western practices, primarily for extremely effective therapy for drug addictions, but also for physical energy, cognitive performance in smaller microdoses, and a surge in positive emotions (See additional studies here and here.).  To microdose with Iboga, you will want to find it in tincture or root bark form (the root bark form is typically encapsulated). If using a tincture, find a source that has the root bark extracted into its purest form, combined with Iboga alkaloids, which keeps the full spectrum of the plant untouched. Just a single drop of an Iboga tincture equates to about 0.5 milligrams and suffices as a microdose. For the root bark of Iboga, a dose of 300-500 milligrams is also an effective dose. I’ve personally found Iboga to be most useful prior to a workout or an effort that combines both brain and body demands, such as tennis or basketball – but it makes you hyperactive and jittery if taken prior to a day of desk work. This makes sense when you consider that African tribes traditionally whipped themselves into a frenzied pre-battle state on Iboga.
I have elsewhere remarked on the apparent lack of benefit to taking multivitamins and the possible harm; so one might well wonder about a specific vitamin like vitamin D. However, a multivitamin is not vitamin D, so it’s no surprise that they might do different things. If a multivitamin had no vitamin D in it, or if it had vitamin D in different doses, or if it had substances which interacted with vitamin D (such as calcium), or if it had substances which had negative effects which outweigh the positive (such as vitamin A?), we could well expect differing results. In this case, all of those are true to varying extents. Some multivitamins I’ve had contained no vitamin D. The last multivitamin I was taking both contains vitamins used in the negative trials and also some calcium; the listed vitamin D dosage was a trivial ~400IU, while I take >10x as much now (5000IU).
Tempted to skip breakfast? Studies have found that eating breakfast may improve short-term memory and attention. Students who eat it tend to perform better than those who don’t. Foods at the top of researchers' brain-fuel list include high-fiber whole grains, dairy, and fruits. Just don't overeat; researchers also found high-calorie breakfasts appear to hinder concentration.
The human drive to be smarter is a familiar theme on the big screen. In 2011, Oscar-nominated actor Bradley Cooper played struggling writer Eddie Morra in the sci-fi thriller Limitless. In the film, Morra acquires a (fictitious) nootropic NZT-48 that allows him to access 100 percent of his mind. Although he finds himself in lots of trouble, his use of the nootropic transforms him from a desperate writer to a multimillionaire who ultimately runs for the U.S. Senate. The film is a testament to a dream deeply entrenched in the American psyche – that an everyman can become superhuman and lead an extraordinary life.
The word “nootropic” was coined in 1972 by a Romanian scientist, Corneliu Giurgea, who combined the Greek words for “mind” and “bending.” Caffeine and nicotine can be considered mild nootropics, while prescription Ritalin, Adderall and Provigil (modafinil, a drug for treating narcolepsy) lie at the far end of the spectrum when prescribed off-label as cognitive enhancers. Even microdosing of LSD is increasingly viewed as a means to greater productivity.
The Neurohacker Collective is a group of scientists, academics, and creatives who, among other things, sell nootropics. One of its premier products is Qualia Original Stack (OS), which has 41 ingredients. The large print says it improves focus, mood, and energy within 30 minutes and “supports long-term brain health.” A 22-dose supply costs $129. Such stacks operate on the idea that synergies among ingredients yield additional benefits.
Factor analysis. The strategy: read in the data, drop unnecessary data, impute missing variables (data is too heterogeneous and collected starting at varying intervals to be clean), estimate how many factors would fit best, factor analyze, pick the ones which look like they match best my ideas of what productive is, extract per-day estimates, and finally regress LLLT usage on the selected factors to look for increases.
You would have heard this advice from top achievers in any field, “Work Smarter, not Harder.” Then why not extend the same philosophy in all areas of your life? Are you smarting from a situation wherein no matter how much you exercise, eat healthy, and sleep well, you still find it a struggle to focus and motivate yourself? If yes, you need smart help that is not hard on you. Try ‘Smart Drugs’, that could help you come out of your situation, by speeding up your thought process, boosting your memory, and making you more creative and productive.

That left me with 329 days of data. The results are that (correcting for the magnesium citrate self-experiment I was running during the time period which did not turn out too great) days on which I happened to use my LED device for LLLT were much better than regular days. Below is a graph showing the entire MP dataseries with LOESS-smoothed lines showing LLLT vs non-LLLT days:

…Four subjects correctly stated when they received nicotine, five subjects were unsure, and the remaining two stated incorrectly which treatment they received on each occasion of testing. These numbers are sufficiently close to chance expectation that even the four subjects whose statements corresponded to the treatments received may have been guessing.
Difficulty concentrating.  As mentioned previously, this may not be a direct result of age—though it can be a common side-effect of struggling with fatigue and brain fog.  When it takes more mental energy to think, it is harder to stay with it for a long time.  Many of us also are surrounded by distractions clambering for our limited attention.  Modern life is fast-paced, stressful, and overcrowded.
The use of prescription stimulants is especially prevalent among students.[9] Surveys suggest that 0.7–4.5% of German students have used cognitive enhancers in their lifetime.[10][11][12] Stimulants such as dimethylamylamine and methylphenidate are used on college campuses and by younger groups.[13] Based upon studies of self-reported illicit stimulant use, 5–35% of college students use diverted ADHD stimulants, which are primarily intended for performance enhancement rather than as recreational drugs.[14][15][16] Several factors positively and negatively influence an individual's willingness to use a drug for the purpose of enhancing cognitive performance. Among them are personal characteristics, drug characteristics, and characteristics of the social context.[10][11][17][18]