Nootropics include natural and manmade chemicals that produce cognitive benefits. These substances are used to make smart pills that deliver results for enhancing memory and learning ability, improving brain function, enhancing the firing control mechanisms in neurons, and providing protection for the brain. College students, adult professionals, and elderly people are turning to supplements to get the advantages of nootropic substances for memory, focus, and concentration.
70 pairs is 140 blocks; we can drop to 36 pairs or 72 blocks if we accept a power of 0.5/50% chance of reaching significance. (Or we could economize by hoping that the effect size is not 3.5 but maybe twice the pessimistic guess; a d=0.5 at 50% power requires only 12 pairs of 24 blocks.) 70 pairs of blocks of 2 weeks, with 2 pills a day requires (70 \times 2) \times (2 \times 7) \times 2 = 3920 pills. I don’t even have that many empty pills! I have <500; 500 would supply 250 days, which would yield 18 2-week blocks which could give 9 pairs. 9 pairs would give me a power of:
A total of 14 studies surveyed reasons for using prescription stimulants nonmedically, all but one study confined to student respondents. The most common reasons were related to cognitive enhancement. Different studies worded the multiple-choice alternatives differently, but all of the following appeared among the top reasons for using the drugs: “concentration” or “attention” (Boyd et al., 2006; DeSantis et al., 2008, 2009; Rabiner et al., 2009; Teter et al., 2003, 2006; Teter, McCabe, Cranford, Boyd, & Guthrie, 2005; White et al., 2006); “help memorize,” “study,” “study habits,” or “academic assignments” (Arria et al., 2008; Barrett et al., 2005; Boyd et al., 2006; DeSantis et al., 2008, 2009; DuPont et al., 2008; Low & Gendaszek, 2002; Rabiner et al., 2009; Teter et al., 2005, 2006; White et al., 2006); “grades” or “intellectual performance” (Low & Gendaszek, 2002; White et al., 2006); “before tests” or “finals week” (Hall et al., 2005); “alertness” (Boyd et al., 2006; Hall et al., 2005; Teter et al., 2003, 2005, 2006); or “performance” (Novak et al., 2007). However, every survey found other motives mentioned as well. The pills were also taken to “stay awake,” “get high,” “be able to drink and party longer without feeling drunk,” “lose weight,” “experiment,” and for “recreational purposes.”
Some data suggest that cognitive enhancers do improve some types of learning and memory, but many other data say these substances have no effect. The strongest evidence for these substances is for the improvement of cognitive function in people with brain injury or disease (for example, Alzheimer's disease and traumatic brain injury). Although "popular" books and companies that sell smart drugs will try to convince you that these drugs work, the evidence for any significant effects of these substances in normal people is weak. There are also important side-effects that must be considered. Many of these substances affect neurotransmitter systems in the central nervous system. The effects of these chemicals on neurological function and behavior is unknown. Moreover, the long-term safety of these substances has not been adequately tested. Also, some substances will interact with other substances. A substance such as the herb ma-huang may be dangerous if a person stops taking it suddenly; it can also cause heart attacks, stroke, and sudden death. Finally, it is important to remember that products labeled as "natural" do not make them "safe."
Another study on the olfactory impact of essential oils like lavender and rosemary revealed that they produced positive effects on cognitive performance and mood.16 And in another study on the inhalation of essential oils like grapefruit, fennel, Estragon, and black pepper essential oil, inhalation of the oils resulted in modulation of sympathetic activity in adults.17,18

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]