If I stop tonight and do nothing Monday (and I sleep the normal eight hours and do not pay any penalty), then that’ll be 4 out of 5 days on modafinil, each saving 3 or 4 hours. Each day took one pill which cost me $1.20, but each pill saved let’s call it 3.5 hours; if I value my time at minimum wage, or 7.25/hr (federal minimum wage), then that 3.5 hours is worth $25.37, which is much more than $1.20, ~21x more.
Last April the scientific journal Nature published the results of an informal online poll asking whether readers attempted to sharpen "their focus, concentration, or memory" by taking drugs such as Ritalin and Provigil, a newer kind of stimulant, known generically as modafinil, which was developed to treat narcolepsy. One in five respondents said they did. A majority of the 1,400 readers who responded said that healthy adults should be permitted to take brain boosters for non-medical reasons, and 69% said that mild side-effects were an acceptable risk. Though a majority said that such drugs should not be made available to children who had no diagnosed medical condition, a third admitted that they would feel pressure to give "smart drugs" to their kids if they learned that other parents were doing so.

Brain focus pills largely contain chemical components like L-theanine which is naturally found in green and black tea. It’s associated with enhancing alertness, cognition, relaxation, arousal, and reducing anxiety to a large extent.  Theanine is an amino and glutamic acid that has been proven to be a safe psychoactive substance. There are studies that suggest that this compound influences, the expression in the genes present in the brain which is responsible for aggression, fear and memory. This, in turn, helps in balancing the behavioural responses to stress and also helps in improving specific conditions, like Post Traumatic Stress Disorder (PTSD).

The NIDA research study focused on 10 healthy male participants. The men were subjected to two rounds of PET brain scans after consuming either Provigil (200 mg or 400 mg) or a placebo. The scans demonstrated that the Provigil users had an increase in the amount of dopamine in the brain. Dopamine is a key neurological messenger in the brain’s reward system. Cocaine and methamphetamine have a similar effect on the brain, but they are more potent and faster-acting than Provigil. As cocaine and amphetamines are addiction-forming, the reasoning here is that Provigil may also be addictive.
Kratom (Erowid, Reddit) is a tree leaf from Southeast Asia; it’s addictive to some degree (like caffeine and nicotine), and so it is regulated/banned in Thailand, Malaysia, Myanmar, and Bhutan among others - but not the USA. (One might think that kratom’s common use there indicates how very addictive it must be, except it literally grows on trees so it can’t be too hard to get.) Kratom is not particularly well-studied (and what has been studied is not necessarily relevant - I’m not addicted to any opiates!), and it suffers the usual herbal problem of being an endlessly variable food product and not a specific chemical with the fun risks of perhaps being poisonous, but in my reading it doesn’t seem to be particularly dangerous or have serious side-effects.
Cephalon executives have repeatedly said that they do not condone off-label use of Provigil, but in 2002 the company was reprimanded by the FDA for distributing marketing materials that presented the drug as a remedy for tiredness, "decreased activity" and other supposed ailments. And in 2008 Cephalon paid $425m and pleaded guilty to a federal criminal charge relating to its promotion of off-label uses for Provigil and two other drugs. Later this year, Cephalon plans to introduce Nuvigil, a longer-lasting variant of Provigil. Candace Steele, a spokesperson, said: "We're exploring its possibilities to treat excessive sleepiness associated with schizophrenia, bipolar depression, traumatic injury and jet lag." Though she emphasised that Cephalon was not developing Nuvigil as a neuroenhancer, she noted: "As part of the preparation for some of these diseases, we're looking to see if there's improvement in cognition."
Of course learning, working memory and cognitive control represent just a few aspects of thinking. Farah concluded that studies looking at other kinds of cognition - verbal fluency, for instance - were too few and too contradictory to tell us much. Both Chatterjee and Farah have wondered whether drugs that heighten users' focus might dampen their creativity. After all, some of our best ideas come to us not when we sit down at a desk but rather when we're in the shower or walking the dog - letting our minds roam. Jimi Hendrix reported that the inspiration for "Purple Haze" came to him in a dream; the chemist Friedrich August Kekule claimed that he discovered the ring structure of benzene during a reverie in which he saw the image of a snake biting its tail. Farah told me: "There is some evidence that suggests that individuals who are better able to focus on one thing and filter out distractions tend to be less creative.
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]