Caffeine works, and it works better with L-theanine, an amino acid from green tea: same alertness, less jitter, fewer afternoon crashes ¹, ².

Creatine is not just for the gym. It props up working memory and reasoning, most when the brain is stressed — vegetarian, sleep-short, grinding ³. Six trials confirm the signal ⁴.

Modafinil is the one prescription case with steady gains in healthy adults: better attention, planning, and learning on hard tasks ⁵. The Limitless version isn't in the data; the felt experience is hours passing without registering, which reads as focus from the inside.

Everything exotic underperforms. Piracetam: no convincing benefit ⁶. Lion's mane: one small trial, gone four weeks after stopping ⁷. Ginkgo: a six-year trial closed the question ⁸.

The whole reliable stack is four daily habits, all cheap.

Modafinil is a different shelf: only with a clinician, for a diagnosed reason. Its marginal gain over the stack above is small and the cardiovascular cost isn't ⁹.

The biggest cognitive levers aren't supplements. They just don't come in a bottle. One night of short sleep produces bigger attention and memory losses than any pill reverses ¹⁰. Aerobic exercise beats every nootropic in the literature ¹¹, and a single walk sharpens memory hours later ¹². Fixing sleep, a daily walk, and morning daylight moves cognition more than everything in the speculative tier combined.

What you can expect on the stack.

• Week one: mostly the 2 pm cutoff. You fall asleep faster, and that's most of the early lift.
• Weeks two to three: creatine's pool fills, the L-theanine smooths the caffeine curve. Subtle — a shallower afternoon trough, a steadier mood.
• Week four on: the 3 pm meeting goes like the 10 am one. Not transformed, just the machinery working as it should, for under a hundred dollars a year.