Nootropics, aka, smart drugs, are supplements that enhance your cognitive functions like memory and creativity. Caffeine is one of the most common nootropic and it is found to increase alertness and attention. Another compound that is shown be psychoactive is L-Theanine. It is usually found in tea and has been shown to mitigate the negative effects of caffeine. L-Theanine seems to increase brain concentrations of serotonin and dopamine.
Unlike NZT from the movie Limitless, nootropics in real life have a much milder effect. And this comes with a catch. Most of these drugs have recorded side effect both short term and long term.
There are other drug-free options to achieve cognitive benefits. Exercising regularly, getting enough sleep, Blue light in the morning are some examples.