Caffeine works in several ways:
- It acts as a reinforcing agent, increasing the likelihood that you'll engage in a certain activity or consume a certain food or beverage.
- It stimulates the release of dopamine and acetylcholine, neuromodulators in the forebrain, which enhance our ability to think and adjust our strategies for different situations.
- It increases the number and efficacy of dopamine receptors in the reward pathways of the brain, making things that would feel good feel even better.
- It acts as an antagonist to adenosine, offsetting the sleepiness that we would otherwise feel from the accumulation of adenosine that occurs as we are awake for more and more hours throughout the day.
In terms of timing and impact, when we ingest caffeine, we generally experience an increase in alertness within about five minutes. This increase in focus and alertness peaks around 30 minutes after ingestion and persists for as long as 60 minutes. It's also been shown to reduce our reaction time and improve our ability to recall information.