Caffeine is a bitter substance that is found in tea, chocolate and soft drinks. According to the Virtual Mass Spectrometry Laboratory (VMSL) at Carnegie Mellon University, caffeine is the most commonly used drug in the world. Caffeine is a stimulant that affects the central nervous system. Sensitivity to caffeine's effects depends on body mass, age, genetic makeup and consumption.
Increases Blood Pressure
According to Mayo Clinic, two to three cups of coffee may cause a sharp and quick increase in blood pressure. VMSL reports that caffeine stimulates the heart while dilating blood vessels, causing increases in pressure. Persons who are concerned about caffeine's influence on blood pressure should limit caffeine intake to less than 200 mg per day.
Boosts Energy
Caffeine is absorbed through the stomach lining and enters the bloodstream within 45 minutes. The caffeine travels to the brainstem and the cerebral cortex, both directly linked to the central nervous system. Caffeine increases energy and feelings of alertness and wakefulness. Iowa State University (ISU) reports that several studies demonstrate that caffeine prolongs physical endurance and delays exercise exhaustion. ISU also notes that most research participants have been male; the findings may not be completely representative of caffeine's effects on women.
Relaxes Bronchial Tubes
Caffeine is a bronchial relaxant that reduces symptoms of asthma. The University of Indiana conducted a 2010 study evaluating caffeine's role in the treatment of exercise-induced asthma. Research revealed that caffeine consumption within an hour of exercise diminished asthmatic symptoms, including wheezing and labored breathing. Nine milligrams of caffeine per kilogram of body weight treated asthmatic symptoms as effectively as an albuterol inhaler.
May Cause Negative Side Effects
Caffeine dosages affect people differently. Typically, 200 to 300 mg of caffeine a day does not produce adverse side effects. When someone exceeds her personal threshold for caffeine intake, she may experience negative side effects. Restlessness, jittery feelings, loss of fine motor control, headaches, dizziness, irregular heartbeats, agitation and insomnia are all negative side effects of consuming too much caffeine. Caffeine may interfere with sleeping quality and patterns. For example, drinking coffee may make it hard to fall asleep at night, and a person may not meet her sleep needs. As a result, she experiences daytime sleepiness the next day and tries to fix the fatigue with caffeine. The cycle repeats, and caffeine becomes a crutch to mask her sleep deprivation.
Creates Dependency
VSML reports that caffeine is an addictive substance; consumption leads to cravings and dependency. Over time, the body adjusts to caffeine levels and increases tolerance to caffeine's effects. According to Mayo Clinic, cutting back on caffeine can cause anxiety, headaches, irritability and nervousness.
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