Ingesting caffeine can stimulate your central nervous system, giving you a mood boost and increased mental acuity. It is classified as a stimulant, the only stimulant classified as safe and effective by the U.S. Food and Drug Administration to be used in over-the-counter products. Caffeine is the most widely used psychoactive compound in the United States due to its effects on brain function.
Mechanism
Caffeine is a chemical compound in the xanthine family. Its mechanism of action is related to another xanthine compound, adenosine. Adenosine, a chemical found in abundance in the human body, accumulates in your brain as you are awake and begins to attach to cells that are responsible for wakeful arousal, inhibiting their action and causing drowsiness and relaxation. When caffeine is present in adequate doses in the human system, it attaches to the same receptor sites to which adenosine does but does not cause sedation. Caffeine induces alertness and mental acuity by inhibiting the action of adenosine.
Increased and prolonged neuron firing in the brain due to adenosine inhibition causes the pituitary gland to react as if there is an emergency situation, producing adrenaline, which can also induce increased mental focus and function. The University of Rochester reports that caffeine also increases dopamine levels in the brain, potentially causing euphoria and increased motivation to complete tasks.
Effects
The physical effects of caffeine include an elevated mood and feelings of well-being. Caffeine also decreases your perception of fatigue and drowsiness, helping your central nervous system to remain alert. You may be able to participate in intellectual activities for longer periods of time, and normally boring tasks may seem more interesting. Although there may be an increased flow of thoughts and perceived mental acuity, the University of Utah College of Pharmacy reports that measured intelligence does not increase with caffeine intake.
Dosage
The effective dose of caffeine varies from person to person. Variables that contribute to the optimal dose to achieve increased brain function include the time of day the dose is taken, tolerance, whether you are fatigued or adequately rested, and whether you smoke or take birth control pills. Adrienne Baxter, a registered dietitian with the University of Kansas Medical Center, reports that around 2 to 5 cups of coffee per day is a safe dosage for most individuals; dosages above this amount have been associated with adverse effects.
Safety
You may experience adverse effects, like extreme nervousness and irritability, if you ingest high doses of caffeine. You may be at risk for developing dependence on the chemical as well if you take it to study or perform other routine tasks every day. Some people are extra sensitive to caffeine and may experience adverse effects at lower dosages.
References
- Wellesley College Chemistry Department; Caffeine; Paul Reisberg; September 1997
- University of Utah College of Pharmacy: Common Meds: Caffeine
- "Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations"; Committee on Military Nutrition Research, Food and Nutrition Board; 2001
- Drury University; Caffeine: How Much Is Too Much?; Amanda Foster
- University of Rochester Health Service: Health Topics: Caffeine
