What does the research actually say?

Bacopa monnieri is an Ayurvedic herb used traditionally to support memory. Randomised trials in healthy older adults found better verbal learning and delayed recall after about 12 weeks. A meta-analysis of nine trials found faster attention (Trail B) and choice reaction time. It is slow to act and commonly causes gut side effects.

Caffeine is the world's most widely used psychoactive compound, a methylxanthine that works by blocking adenosine receptors. At low to moderate doses it reliably improves alertness, vigilance, attention and reaction time, with weaker and less consistent effects on memory and higher-order judgement. It is the reference point every other stimulant on this wiki gets compared to.

L-theanine is an amino acid found almost only in tea. Taken at 200 to 400 mg a day, it may reduce stress and anxiety in people under stressful conditions. Its best-known use is alongside caffeine, where the pair improves attention switching more than either alone. A 2025 meta-analysis found small improvements in subjective sleep.

Magnesium is an essential mineral sold in many salt forms. Meta-analyses of randomised trials find modest drops in blood pressure, largest in people with hypertension or low magnesium. They also find improved insulin resistance with longer use and fewer migraine attacks. Evidence for sleep and depression is weaker but positive. Which salt matters less than marketing suggests.

Melatonin is the hormone the pineal gland releases at night to signal darkness. Taken as a supplement, its most convincing use is jet lag, where a Cochrane review put the number needed to treat at 2. For insomnia the benefit is real but modest: about 7 minutes faster sleep onset and 8 minutes more sleep on average. Timing matters as much as dose.

Modafinil is a prescription wakefulness-promoting drug for narcolepsy, obstructive sleep apnoea and shift work sleep disorder. It is widely used off-label as a "smart drug". In healthy people who are not sleep-deprived, a meta-analysis found only a small overall cognitive effect, driven mainly by memory updating.

Piracetam is the original "nootropic". C. Giurgea developed it in the late 1960s and coined the word to describe it. It is licensed in several countries for cognitive disorders, vertigo and cortical myoclonus. The evidence is mixed. An older meta-analysis found a global benefit in older adults with cognitive impairment, but a 2024 meta-analysis could not confirm an effect on memory.