Black coffee provides a rich source of caffeine when you need it the most. CNN Health reports that over half of American adults drink coffee every day and coffee drinkers generally consume approximately three cups of their favorite java per day. That amount of caffeine may be the greatest concern of coffee's effects on your body, although coffee's effects aren't all problematic.
A standard 8-ounce cup of black coffee contains approximately 95 to 200 milligrams of caffeine, which is enough to get your heart racing and significantly increase your energy. Caffeine stimulates your central nervous system, which contributes to the elevated energy effect. A cup of coffee can also temporarily alleviate fatigue. Along with physical energy, coffee has an effect on mental energy as well; improving concentration, focus and mental alertness.
Another beneficial effect coffee has on your body is helping protect it from oxidation damage from free radicals such as ultra-violet rays, air pollutants and cigarette smoke. This is due to black coffee's antioxidant agents, flavonoids, which are the same type of antioxidants that exist in tea, red wine and chocolate. Due to America's habitual coffee habit, Joe A. Vinson, Ph.D., reports at CNN Health that coffee is the leading source of antioxidants in the American diet. It does not have higher antioxidant content than other foods and drinks, but because it is so frequently consumed it provides a substantial amount of antioxidants.
Effects on Sleep
The caffeine content in black coffee may help you stay awake, but, ironically, it may also inhibit falling asleep. Caffeine is in your system for many hours after it's consumed, so your coffee break in the middle of the day may keep your mind running into the night. Chronic sleep loss -- less than 7 hours per night -- can lead to health problems including diabetes, heart attack and even obesity, according to the book Sleep Disorders and Sleep Deprivation: An Unmet Public Health Problem, published by The National Academies. So, if you consume coffee throughout the day and experience symptoms of insomnia at night, try cutting back on your afternoon coffee. If you still can't fall asleep after reducing coffee consumption, talk with your doctor about other possible sleep complications.
Coffee can cause problematic effects to your body, other than just sleep complications. If you are sensitive to caffeine or consume excessive amounts of coffee, over four cups a day, you may experience side effects such as nervousness, restlessness and irritability. It may also cause physical effects including stomach upset, headache, irregular heartbeat and muscle tremors. Caffeine is hard on your liver and can interact with alcohol and certain medications that are also hard on your liver. Talk with your doctor about your current medications and caffeine intake if you regularly consume coffee or other caffeinated beverages.