The first night I was eating some coconut oil, I did my n-backing past 11 PM; normally that damages my scores, but instead I got 66/66/75/88/77% (▁▁▂▇▃) on D4B and did not feel mentally exhausted by the end. The next day, I performed well on the Cambridge mental rotations test. An anecdote, of course, and it may be due to the vitamin D I simultaneously started. Or another day, I was slumped under apathy after a promising start to the day; a dose of fish & coconut oil, and 1 last vitamin D, and I was back to feeling chipper and optimist. Unfortunately I haven’t been testing out coconut oil & vitamin D separately, so who knows which is to thank. But still interesting.
If you are a slow caffeine metabolizer and consume too much caffeine, you run the risk of mild to severe complications, such as cardiovascular disease. There’s also the sleep disruption problem of having too much caffeine left in your bloodstream late in the day as a result of a longer caffeine half-life, a problem not faced by fast caffeine metabolizers (it’s so unfair if you love your cup of joe, right?). In addition, fast caffeine metabolizers actually run a reduced risk of cardiovascular complications if they consume at least one cup of coffee per day. While anyone can be a slow caffeine metabolizer, there are certain ethnic backgrounds that are indeed associated with slower and faster caffeine metabolisms. For example, it’s known that people with Asian and African ethnic backgrounds generally have slower rates of caffeine metabolism. To find out if you’re a fast or slow caffeine metabolizer, you can have a relatively inexpensive salivary genetic test performed by a company like 23andme and then use the online dashboard to jump straight to your CYP1A2 gene. When you’re there, you type into the search bar “rs762551”. If your rs762551 SNP variant is AA, then you’re a fast caffeine metabolizer, but if your variant is AC or CC, you’re a slow caffeine metabolizer. Fortunately, many genetic testing companies will now simply report directly on your results whether you’re a slow or fast metabolizer, without you needing to go through the SNP searching trouble.
This is why it was so refreshing to stumble across Dr. Lisa Mosconi's new book "Brain Food: The Surprising Power of Eating for Cognitive Power" . "Our brains aren't keeping up with the historical change in dietary consumptions", says Dr. Lisa. And it's quite evident in her book when she does a historical overview and draws an important relationship between what our ancestors were eating and the concept of longevity. Her contribution to the fascinating new world of "neuro-nutrition" differs drastically from the diet culture we are all so used to and can help us understand why including (and excluding) certain foods, will actually boost our brain health. 
The principal metric would be mood, however defined. Zeo’s web interface & data export includes a field for Day Feel, which is a rating 1-5 of general mood & quality of day. I can record a similar metric at the end of each day. 1-5 might be a little crude even with a year of data, so a more sophisticated measure might be in order. The first mood study is paywalled so I’m not sure what they used, but Shiotsuki 2008 used State-Trait of Anxiety Inventory (STAI) and Profiles of Mood States Test (POMS). The full POMS sounds too long to use daily, but the Brief POMS might work. In the original 1987 paper A brief POMS measure of distress for cancer patients, patients answering this questionnaire had a mean total mean of 10.43 (standard deviation 8.87). Is this the best way to measure mood? I’ve asked Seth Roberts; he suggested using a 0-100 scale, but personally, there’s no way I can assess my mood on 0-100. My mood is sufficiently stable (to me) that 0-5 is asking a bit much, even.
Analyzing the results is a little tricky because I was simultaneously running the first magnesium citrate self-experiment, which turned out to cause a quite complex result which looks like a gradually-accumulating overdose negating an initial benefit for net harm, and also toying with LLLT, which turned out to have a strong correlation with benefits. So for the potential small Noopept effect to not be swamped, I need to include those in the analysis. I designed the experiment to try to find the best dose level, so I want to look at an average Noopept effect but also the estimated effect at each dose size in case some are negative (especially in the case of 5-pills/60mg); I included the pilot experiment data as 10mg doses since they were also blind & randomized. Finally, missingness affects analysis: because not every variable is recorded for each date (what was the value of the variable for the blind randomized magnesium citrate before and after I finished that experiment? what value do you assign the Magtein variable before I bought it and after I used it all up?), just running a linear regression may not work exactly as one expects as various days get omitted because part of the data was missing.
Working memory has been likened to a mental scratch pad: you use it to keep relevant data in mind while you're completing a task. (Imagine a cross-examination, in which a lawyer has to keep track of the answers a witness has given and formulate new questions based on them.) In one common test subjects are shown a series of items - usually letters or numbers - and then presented with challenges: was this number or letter in the series? Was this one? In the working-memory tests, subjects performed better on neuroenhancers, though several of the studies suggested that the effect depended on how good a subject's working memory was to begin with: the better it was, the less benefit the drugs provided.
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.
Bacopa is a supplement herb often used for memory or stress adaptation. Its chronic effects reportedly take many weeks to manifest, with no important acute effects. Out of curiosity, I bought 2 bottles of Bacognize Bacopa pills and ran a non-randomized non-blinded ABABA quasi-self-experiment from June 2014 to September 2015, measuring effects on my memory performance, sleep, and daily self-ratings of mood/productivity. Because of the very slow onset, small effective sample size, definite temporal trends probably unrelated to Bacopa, and noise in the variables, the results were as expected, ambiguous, and do not strongly support any correlation between Bacopa and memory/sleep/self-rating (+/-/- respectively).
Some suggested that the lithium would turn me into a zombie, recalling the complaints of psychiatric patients. But at 5mg elemental lithium x 200 pills, I’d have to eat 20 to get up to a single clinical dose (a psychiatric dose might be 500mg of lithium carbonate, which translates to ~100mg elemental), so I’m not worried about overdosing. To test this, I took on day 1 & 2 no less than 4 pills/20mg as an attack dose; I didn’t notice any large change in emotional affect or energy levels. And it may’ve helped my motivation (though I am also trying out the tyrosine).
Noopept is a Russian stimulant sometimes suggested for nootropics use as it may be more effective than piracetam or other -racetams, and its smaller doses make it more convenient & possibly safer. Following up on a pilot study, I ran a well-powered blind randomized self-experiment between September 2013 and August 2014 using doses of 12-60mg Noopept & pairs of 3-day blocks to investigate the impact of Noopept on self-ratings of daily functioning in addition to my existing supplementation regimen involving small-to-moderate doses of piracetam. A linear regression, which included other concurrent experiments as covariates & used multiple imputation for missing data, indicates a small benefit to the lower dose levels and harm from the highest 60mg dose level, but no dose nor Noopept as a whole was statistically-significant. It seems Noopept’s effects are too subtle to easily notice if they exist, but if one uses it, one should probably avoid 60mg+.

Before you try nootropics, I suggest you start with the basics: get rid of the things in your diet and life that reduce cognitive performance first. That is easiest. Then, add in energizers like Brain Octane and clean up your diet. Then, go for the herbals and the natural nootropics. Use the pharmaceuticals selectively only after you’ve figured out your basics.

Your co-worker in the cubicle next to you could now very likely be achieving his or her hyperfocus via a touch of microdosed LSD, a hit of huperzine or a nicotine-infused arm patch. The fact is, concepts such as microdosing, along with words like “nootropic” and “smart drug” (yes, there’s a difference between the two, as you’re about to discover) are quickly becoming household terms, especially due to all the recent media hype that has disclosed how popular compounds such as smart drugs and psychedelics are among Silicon Valley CEOs and college students, along with the smart drug movies “Limitless” and “Lucy“ and popular TV shows like “Limitless”, “Wormwood” and “Hamilton’s Pharmacopeia”.
Or in other words, since the standard deviation of my previous self-ratings is 0.75 (see the Weather and my productivity data), a mean rating increase of >0.39 on the self-rating. This is, unfortunately, implying an extreme shift in my self-assessments (for example, 3s are ~50% of the self-ratings and 4s ~25%; to cause an increase of 0.25 while leaving 2s alone in a sample of 23 days, one would have to push 3s down to ~25% and 4s up to ~47%). So in advance, we can see that the weak plausible effects for Noopept are not going to be detected here at our usual statistical levels with just the sample I have (a more plausible experiment might use 178 pairs over a year, detecting down to d>=0.18). But if the sign is right, it might make Noopept worthwhile to investigate further. And the hardest part of this was just making the pills, so it’s not a waste of effort.
Perhaps the most well-known natural nootropic stimulant and neuroenhancer is caffeine. Caffeine has been shown to prevent memory deficits in experimental models of Alzheimer’s disease and may even restore memory following impairment. In studies performed with college students, caffeine was shown to have particularly potent effects on memory improvement during students’ non-optimal time of day, in this case, early in the morning. Caffeine’s benefits go even further because it’s never found in an isolated vacuum in nature, meaning that it’s always located in some kind of plant such as green tea or bean such as coffee that carry additional beneficial compounds which often enhance the effects of caffeine, including, most notably, certain cholesterols, polyphenols and antioxidants. In fact, one study determined that caffeine alone does not account for the benefits caused by coffee consumption. Rather, the phytochemical content of coffee (coffee contains over 1,000 different natural chemicals!) gives it potent antioxidant and anti-inflammatory properties that complement the neuroprotective effects of caffeine on the central nervous system.
I’m wary of others, though. The trouble with using a blanket term like “nootropics” is that you lump all kinds of substances in together. Technically, you could argue that caffeine and cocaine are both nootropics, but they’re hardly equal. With so many ways to enhance your brain function, many of which have significant risks, it’s most valuable to look at nootropics on a case-by-case basis. Here’s a list of 13 nootropics, along with my thoughts on each.

Dr. Lisa Mosconi, whose research spans an extraordinary range of specialties including brain science, the microbiome, and nutritional genomics, notes that the dietary needs of the brain are substantially different from those of the other organs, yet few of us have any idea what they might be. Her innovative approach to cognitive health incorporates concepts that most doctors have yet to learn. Busting through advice based on pseudoscience, Dr. Mosconi provides recommendations for a complete food plan, while calling out noteworthy surprises, including why that paleo diet you are following may not be ideal, why avoiding gluten may be a terrible mistake, and how simply getting enough water can dramatically improve alertness. 

One of the most common strategies to beat this is cycling. Users who cycle their nootropics take them for a predetermined period, (usually around five days) before taking a two-day break from using them. Once the two days are up, they resume the cycle. By taking a break, nootropic users reduce the tolerance for nootropics and lessen the risk of regression and tolerance symptoms.
I had tried 8 randomized days like the Adderall experiment to see whether I was one of the people whom modafinil energizes during the day. (The other way to use it is to skip sleep, which is my preferred use.) I rarely use it during the day since my initial uses did not impress me subjectively. The experiment was not my best - while it was double-blind randomized, the measurements were subjective, and not a good measure of mental functioning like dual n-back (DNB) scores which I could statistically compare from day to day or against my many previous days of dual n-back scores. Between my high expectation of finding the null result, the poor experiment quality, and the minimal effect it had (eliminating an already rare use), the value of this information was very small.
Next generation medical imaging and genomic sequencing studies, including my own work, have helped reveal that some foods are neuro-protective, literally shielding the brain from harm and supporting cognitive fitness over the course of a lifetime. Conversely, other foods are harmful for the brain, slowing us down in general, making us feel sluggish and tired, while at the same time increasing our risk of dementia.
So the chi-squared believes there is a statistically-significant difference, the two-sample test disagrees, and the binomial also disagrees. Since I regarded it as a dubious theory, can’t see a difference, and the binomial seems like the most appropriate test, I conclude that several months of 1mg iodine did not change my eye color. (As a final test, when I posted the results on the Longecity forum where people were claiming the eye color change, I swapped the labels on the photos to see if anyone would claim something along the lines when I look at the photos, I can see a difference!. I thought someone might do that, which would be a damning demonstration of their biases & wishful thinking, but no one did.)
Herbs and plants have been used for cognitive enhancement for at least 5,000 years in Indian and Chinese medicine, long before the first synthetic nootropic was created. The practice of Indian Ayurvedic medicine includes the use of a group of nootropic plants known as Medhya Rasayana, the four primary plants of which are Mandukaparni, Yastimadhu, Duduchi and Shankhapushpi, though other lesser known plants are also used. One of the most common supplements in Ayurvedic medicine is Brahmi, known scientifically as “Bacopa monnieri” or “B. monnieri “ and more commonly as water hyssop, Thyme-leaved Gratiola, herb of grace or Indian pennywort. It is named after Lord Brahma, the creator God and originator of Ayurveda, and has been used for centuries to treat disorders ranging from pain and epilepsy to inflammation and memory dysfunction. The exact mechanism behind its action is not fully understood, but it is believed to promote antioxidant activity as well as protect neurons in the prefrontal cortex, hippocampus and corpus striatum against cytotoxicity and DNA damage associated with Alzheimer’s. The prefrontal cortex is critical in rational, social and personality behavior, the hippocampus is believed to be the seat of memory and the autonomic nervous system and the striatum play a role in the reward system of action, so the protection Brahmi provides is extremely helpful in preventing the degeneration of many important cognitive faculties. An effective dose ranges from 300 to 450 mg per day. Winter cherry (ashwagandha) is another well-known Ayurvedic supplement that can promote improved cognitive development, memory and intelligence and reduce the effects of neurodegenerative diseases such as Parkinson’s, Huntington’s and Alzheimer’s. The optimal dose is 6,000 mg per day divided into three 2,000 mg doses. Aloeweed (shankhpushpi) is also used in Ayurvedic medicine to improve memory and intellect as well as treat hypertension, epilepsy and diabetes. Effective doses for most neuroenhancing benefits range as high as 40 g per day.

An unusual intervention is infrared/near-infrared light of particular wavelengths (LLLT), theorized to assist mitochondrial respiration and yielding a variety of therapeutic benefits. Some have suggested it may have cognitive benefits. LLLT sounds strange but it’s simple, easy, cheap, and just plausible enough it might work. I tried out LLLT treatment on a sporadic basis 2013-2014, and statistically, usage correlated strongly & statistically-significantly with increases in my daily self-ratings, and not with any sleep disturbances. Excited by that result, I did a randomized self-experiment 2014-2015 with the same procedure, only to find that the causal effect was weak or non-existent. I have stopped using LLLT as likely not worth the inconvenience.
A record of nootropics I have tried, with thoughts about which ones worked and did not work for me. These anecdotes should be considered only as anecdotes, and one’s efforts with nootropics a hobby to put only limited amounts of time into due to the inherent limits of drugs as a force-multiplier compared to other things like programming1; for an ironic counterpoint, I suggest the reader listen to a video of Jonathan Coulton’s I Feel Fantastic while reading.
If you want to focus on boosting your brain power, Lebowitz says you should primarily focus on improving your cardiovascular health, which is "the key to good thinking." For example, high blood pressure and cholesterol, which raise the risk of heart disease, can cause arteries to harden, which can decrease blood flow to the brain. The brain relies on blood to function normally.
In fact, this body-mind connection has become so relevant to our current era that communities like Mental Health America are devoting their efforts to create a challenge that raises awareness on how lifestyle plays an important role on our mental health. While our generation is definitely more conscious of our bodies and the importance of a healthy lifestyle, it's a good reminder that the body is like a machine and we should listen to it, tune it up, and update the system every so often. 

One should note the serious caveats here: it is a small in vitro study of a single category of human cells with an effect size that is not clear on a protein which feeds into who-knows-what pathways. It is not a result in a whole organism on any clinically meaningful endpoint, even if we take it at face-value (many results never replicate). A look at followup work citing Rapuri et al 2007 is not encouraging: Google Scholar lists no human studies of any kind, much less high-quality studies like RCTs; just some rat followups on the calcium effect. This is not to say Rapuri et al 2007 is a bad study, just that it doesn’t bear the weight people are putting on it: if you enjoy caffeine, this is close to zero evidence that you should reduce or drop caffeine consumption; if you’re taking too much caffeine, you already have plenty of reasons to reduce; if you’re drinking lots of coffee, you already have plenty of reasons to switch to tea; etc.
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.
If you’re a coffee or tea drinker, keep sipping: Caffeine may help protect against age-related cognitive decline. “Studies have indicated that caffeine—for example, roughly 500 milligrams daily, the equivalent of about five cups of coffee—may help stave off memory issues in humans,” says Bruce Citron, PhD, a neuroscientist at Bay Pines VA Healthcare System and the USF Morsani College of Medicine in Florida. (Experts warn against taking caffeine supplements, which flood your body with a lot of caffeine all at once.)
You have probably heard and you already love the term “soul food.” You should know that there’s “brain food” too. Natural supplements are the best way to express your gratitude for all the hard work your brain does for you around the clock. These products aren’t reserved only for the elderly users. On the contrary, if you start using them while you’re still young and sharp, you can ensure the proper protection against all those age-related mental deterioration processes.
One of the most common strategies to beat this is cycling. Users who cycle their nootropics take them for a predetermined period, (usually around five days) before taking a two-day break from using them. Once the two days are up, they resume the cycle. By taking a break, nootropic users reduce the tolerance for nootropics and lessen the risk of regression and tolerance symptoms.