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.
l-Theanine – A 2014 systematic review and meta-analysis found that concurrent caffeine and l-theanine use had synergistic psychoactive effects that promoted alertness, attention, and task switching;[29] these effects were most pronounced during the first hour post-dose.[29] However, the European Food Safety Authority reported that, when L-theanine is used by itself (i.e. without caffeine), there is insufficient information to determine if these effects exist.[34]
Modafinil is not addictive but there may be chances of drug abuse and memory impairment.  This can manifest in people who consume it to stay up for way too long, as a result, this would probably make them sick. Long-term use of Modafinil may reduce plasticity and can have an adverse effect on the memory of some individuals. Hence it is sold only on prescription by a qualified physician.
It seems like we're constantly bombarded by the newest superfoods, how matcha is the coffee, and why Himalayan salt is "so much better" than sea salt (spoiler alert: it's not, but its pink hue definitely makes cooking more fun). Dieting has always been an on/off kind of activity in my life which is why I've struggled to jump on this train for a while.
As with any thesis, there are exceptions to this general practice. For example, theanine for dogs is sold under the brand Anxitane is sold at almost a dollar a pill, and apparently a month’s supply costs $50+ vs $13 for human-branded theanine; on the other hand, this thesis predicts downgrading if the market priced pet versions higher than human versions, and that Reddit poster appears to be doing just that with her dog.↩
Alpha GPC + AC-11 + Bacopa Monniera + Huperzine: This combination is found in the supplement Alpha Brain, created by the company Onnit. According to a clinical trial that was conducted by the Boston Center for Memory, this combination has demonstrated a notable increase in cognitive performance for healthy individuals and shows particular potential to boost the memory and learning capacity of users. AC-11 is derived from a rainforest herb, and studies have found that it may be able to help people in a variety of ways such as slowing the growth of cancer due to its DNA repairing antioxidant properties. This stack seems to work best if you take it daily for at about two weeks. After that, effects become more pronounced over time, so, similar to the Gingko, Bacopa, Lion’s Mane stack above you need to allow this blend to build up in your system before you judge its overall effectiveness.

When many of us think of memory enhancers, we think of ginkgo biloba, the herb that now generates more than $240 million in sales a year worldwide. The October 22-29, 1997 issue of the Journal of the American Medical Association reported that Alzheimer's patients who took 120 mg of ginkgo showed small improvements in tests designed to measure mental performance.
Barbara Sahakian, a neuroscientist at Cambridge University, doesn’t dismiss the possibility of nootropics to enhance cognitive function in healthy people. She would like to see society think about what might be considered acceptable use and where it draws the line – for example, young people whose brains are still developing. But she also points out a big problem: long-term safety studies in healthy people have never been done. Most efficacy studies have only been short-term. “Proving safety and efficacy is needed,” she says.

Eugeroics (armodafinil and modafinil) – are classified as "wakefulness promoting" agents; modafinil increased alertness, particularly in sleep deprived individuals, and was noted to facilitate reasoning and problem solving in non-ADHD youth.[23] In a systematic review of small, preliminary studies where the effects of modafinil were examined, when simple psychometric assessments were considered, modafinil intake appeared to enhance executive function.[27] Modafinil does not produce improvements in mood or motivation in sleep deprived or non-sleep deprived individuals.[28]