I took 1.5mg of melatonin, and went to bed at ~1:30AM; I woke up around 6:30, took a modafinil pill/200mg, and felt pretty reasonable. By noon my mind started to feel a bit fuzzy, and lunch didn’t make much of it go away. I’ve been looking at studies, and users seem to degrade after 30 hours; I started on mid-Thursday, so call that 10 hours, then 24 (Friday), 24 (Saturday), and 14 (Sunday), totaling 72hrs with <20hrs sleep; this might be equivalent to 52hrs with no sleep, and Wikipedia writes:
Googling, you sometimes see correlational studies like Intake of Flavonoid-Rich Wine, Tea, and Chocolate by Elderly Men and Women Is Associated with Better Cognitive Test Performance; in this one, the correlated performance increase from eating chocolate was generally fairly modest (say, <10%), and the maximum effects were at 10g/day of what was probably milk chocolate, which generally has 10-40% chocolate liquor in it, suggesting any experiment use 1-4g. More interesting is the blind RCT experiment Consumption of cocoa flavanols results in acute improvements in mood and cognitive performance during sustained mental effort11, which found improvements at ~1g; the most dramatic improvement of the 4 tasks (on the Threes correct) saw a difference of 2 to 6 at the end of the hour of testing, while several of the other tests converged by the end or saw the controls winning (Sevens correct). Crews et al 2008 found no cognitive benefit, and an fMRI experiment found the change in brain oxygen levels it wanted but no improvement to reaction times.
Choline is a nootropic: it enhances your ability to pay attention and learn efficiently,[18] probably because you use a lot of acetylcholine during mentally-demanding tasks, and choline helps you synthesize enough to work harder and go longer.[19] Choline also links to decreased brain inflammation in a dose-dependent manner — the more choline you eat, the less inflamed your brain tends to be.[20]

The blood half-life is 12-36 hours; hence two or three days ought to be enough to build up and wash out. A week-long block is reasonable since that gives 5 days for effects to manifest, although month-long blocks would not be a bad choice either. (I prefer blocks which fit in round periods because it makes self-experiments easier to run if the blocks fit in normal time-cycles like day/week/month. The most useless self-experiment is the one abandoned halfway.)

Reason: Acetyl-L-carnitine can protect the brain from neurotoxicity. It can also ward off oxygen deprivation. Acetyl-L-carnitine can even preserve cells energy-producing mitochondria. Plus, it can rejuvenate mental and physical function. Dosages for studies have been in the 1,500 – 4,000 mg range. These are divided into two or three doses. However, we recommend no more than 1,000 mg of acetyl-L-carnitine a day without medical supervision.
And if you obtain your vitamin C from a multivitamin, you receive other key nutrients that many studies over the years have linked to healthy brain function, including beta carotene, iron, zinc, B12 and folic acid. In the June 1999 issue of the Journal of Biology and Psychiatry, for instance, researchers at Sweden's Gotenborg University reported that older people were more likely to score poorly on word memory tests if they had low levels of folic acid.
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).
Be patient.  Even though you may notice some improvements right away (sometimes within the first day), you should give your brain supplement at least several months to work.  The positive effects are cumulative, and most people do not max out their brain potential on a supplement until they have used it for at least 90 days.  That is when the really dramatic effects start kicking in!
People with failing memory and worried about Alzheimer’s disease are sometimes seduced by advertisements for Huperzine A, extracted from a type of moss. Some studies have shown that it increases levels of acetylcholine in the brain, a chemical that is in short supply in Alzheimer’s. But despite increasing acetylcholine, aside from a few questionable studies in China, there is no evidence that it improves memory. Unfortunately when it comes to memory pills, they are best forgotten. There is, however, hope that a nasal spray containing insulin can increase the absorption of glucose into brain cells and improve cognitive function. But in the meantime, the best bet to maintain good brain function is to monitor blood glucose and blood pressure, eat a diet rich in fruits, vegetables and whole grains, and low in simple carbs and saturated fat. And don’t forget that physical exercise also exercises your brain.
One of the most popular legal stimulants in the world, nicotine is often conflated with the harmful effects of tobacco; considered on its own, it has performance & possibly health benefits. Nicotine is widely available at moderate prices as long-acting nicotine patches, gums, lozenges, and suspended in water for vaping. While intended for smoking cessation, there is no reason one cannot use a nicotine patch or nicotine gum for its stimulant effects.
We felt that the price for this product was OK but were concerned about how cheap it was on some websites. Our experience suggests that this could reflect the standard of the product, it could be that the quality of ingredients is poor and the dosage low so that they can price cut, however, this leaves consumers having to take more to reach the same level as other products. This can lead to all sorts of issues regarding overdosing, so for these reasons, until further testing can be carried out, we could not place this higher on our score board.

Eliminating foggy-headedness seems to be the goal of many users of neuroenhancers. But can today's drugs actually accomplish this? I recently posed this question to Chatterjee's colleague Martha Farah, who is a psychologist at Penn and the director of its Center for Cognitive Neuroscience. She is deeply fascinated by, and mildly critical of, neuroenhancers, but basically in favour - with the important caveat that we need to know much more about how these drugs work. While Farah does not take neuroenhancers, she had just finished a paper in which she reviewed the evidence on prescription stimulants as neuroenhancers from 40 laboratory studies involving healthy subjects. Most of the studies looked at one of three types of cognition: learning, working memory, and cognitive control. A typical learning test asks subjects to memorise a list of paired words; an hour, a few days, or a week later, they are presented with the first words in the pairs and asked to come up with the second. Neuroenhancers did improve retention, especially where subjects had been asked to remember information for several days or longer.
The difference in standard deviations is not, from a theoretical perspective, all that strange a phenomenon: at the very beginning of this page, I covered some basic principles of nootropics and mentioned how many stimulants or supplements follow a inverted U-curve where too much or too little lead to poorer performance (ironically, one of the examples in Kruschke 2012 was a smart drug which did not affect means but increased standard deviations).
Omega-3 fatty acids: DHA and EPA – two Cochrane Collaboration reviews on the use of supplemental omega-3 fatty acids for ADHD and learning disorders conclude that there is limited evidence of treatment benefits for either disorder.[42][43] Two other systematic reviews noted no cognition-enhancing effects in the general population or middle-aged and older adults.[44][45]