Creatine is the most thoroughly researched supplement in human history and the most overlooked compound in cognitive enhancement. Working memory improvements confirmed in multiple RCTs. Sleep deprivation cognitive protection confirmed with brain imaging (2024). 30+ years of safety data with no serious adverse effects. Cost: approximately 20–40p per day. This complete guide covers the mechanism, the benchmark trials, why vegetarians show the largest effects, and the Creapure® quality standard that matters.