How Does Caffeine Affect People?

Caffeine occurs naturally in a number of plants, including coffee, tea and cocoa. Once consumed, caffeine enters your bloodstream and interacts with your central nervous system -- your brain and spinal cord -- to produce a range of physiological effects. Caffeine's effect on the nervous system can prove beneficial in some cases, but might also pose a health risk.

Brain Stimulation

One way caffeine affects people is by functioning as a central nervous system stimulant. Caffeine has the ability to interact with specialized proteins, called receptors, located on cells within your brain. Caffeine interacts with adenosine receptors -- normally responsible for inducing feelings of drowsiness -- and prevents their activation. As a result, this inhibition of adenosine signalling helps to prevent fatigue and tiredness, and stimulates your brain activity. This stimulation subsides as your brain eventually breaks down the caffeine, your adenosine receptors can begin to signal again, and you begin to feel less alert as the caffeine "buzz" wears off.

Cognitive Effects

The stimulatory effect of caffeine on your brain can temporarily increase cognitive function. You might notice an increase in alertness and ability to perform cognitive tasks, such as studying or working. In addition, caffeine might have a beneficial effect for individuals suffering from cognitive diseases, such as Alzheimer's disease. A study published in the "Journal of Alzheimer's Disease" in 2009 found that caffeine helped to treat cognitive decline in laboratory mice suffering from Alzheimer's disease. Though caffeine's effect on Alzheimer's disease in humans remains unknown, caffeine might someday present a possible treatment for the cognitive decline experienced in people with Alzheimer's.

Cardiovascular Effects

Caffeine also has an effect on your cardiovascular system. Caffeine activates your sympathetic nervous system, a network of nerves responsible for regulating several processes, including your blood pressure and heart rate. After consuming caffeine, sympathetic nerve activation constricts your blood vessels, increases your blood pressure and heart rate. As a result, consuming caffeine might have an adverse effect on individuals who already suffer from cardiovascular disorders, like hypertension, by further increasing blood pressure.Caffeine's ability to constrict blood vessels can prove useful in treating migraines. If you suffer from a heart condition or frequent migraines, talk to your doctor about the safety of caffeine.

Effect on Sleep

While caffeine has a number of beneficial effects, it can also disrupt your normal sleep patterns. Your body has an internal clock that helps you feel tired at night and helps you wake up in the morning. By acting as a central nervous system stimulant and disrupting your brain's "drowsy" signals, caffeine can temporarily alter your sleep cycle, making it difficult to fall asleep. You can avoid sleep disturbances by avoiding caffeine for several hours before you fall asleep, and reducing your caffeine intake if you experience difficulty sleeping.