Conversely, you have to consider that the long term effects of Modafinil haven’t been studies very well. It significantly upsets sleep cycles, and 50% of Modafinil users report a number of short term side effects, such as mild to severe headaches, insomnia, nausea, anxiety, nervousness, hypertension, decreased appetite, and weight loss. PET scans show it affects the same areas of the brain that are stimulated by substance abuse.
There are many studies that suggest that Creatine helps in treating cognitive decline in individuals when combined with other therapies. It also helps people suffering from Parkinsons and Huntingtons disease. Though there are minimal side effects associated with creatine, pretty much like any nootropic, it is not  absolutely free of side-effects. An overdose of creatine can lead to gastrointestinal issues, weight gain, stress and anxiety.
Mercury, as well as other heavy metals such as lead, can accumulate in brain tissue, as well as in the spinal cord, as they are fat-soluble - meaning that they can hide itself in fat tissue, which is abundant in both the brain and the spine. Once there, they can displace important nutrients for brain health such as zinc and iron, which are needed for neurotransmitter production, as well as induce an inflammatory process called oxidative stress among other things.
My predictions were substantially better than random chance7, so my default belief - that Adderall does affect me and (mostly) for the better - is borne out. I usually sleep very well and 3 separate incidents of horrible sleep in a few weeks seems rather unlikely (though I didn’t keep track of dates carefully enough to link the Zeo data with the Adderall data). Between the price and the sleep disturbances, I don’t think Adderall is personally worthwhile.
You’ve no doubt heard that we’re now entering a new golden age of psychedelics, and microdosing with LSD, psilocybin, ketamine and other compounds previously placed in the realm of party animals and rave enthusiasts is now commonplace for CEO’s, the Navy SEALs, famous authors and beyond. You no longer have to be a tree-hugging, anti-war rebel to achieve the many positive health benefits of psychedelics. My own personal experience with these compounds has spanned several years of quarterly heavy psilocybin and DMT dosages for personal self-discovery, weekly LSD microdoses for creativity and productivity, and iboga microdosing for a pre-workout boost.
This research is in contrast to the other substances I like, such as piracetam or fish oil. I knew about withdrawal of course, but it was not so bad when I was drinking only tea. And the side-effects like jitteriness are worse on caffeine without tea; I chalk this up to the lack of theanine. (My later experiences with theanine seems to confirm this.) These negative effects mean that caffeine doesn’t satisfy the strictest definition of nootropic (having no negative effects), but is merely a cognitive enhancer (with both benefits & costs). One might wonder why I use caffeine anyway if I am so concerned with mental ability.

The main concern with pharmaceutical drugs is adverse effects, which also apply to nootropics with undefined effects. Long-term safety evidence is typically unavailable for nootropics.[13] Racetams — piracetam and other compounds that are structurally related to piracetam — have few serious adverse effects and low toxicity, but there is little evidence that they enhance cognition in people having no cognitive impairments.[19]