"The most renowned effects of caffeine on the body are increased alertness and delay of fatigue and sleep. Caffeine is chemically similar to a chemical in our brains called adenosine. Caffeine interacts with adenosine’s specific protein receptor, blocks the actions of adenosine, and affects the levels of signaling molecules in the brain, leading to an increase in energy metabolism. At the molecular level, caffeine stimulates the brain, increasing alertness and causing a delay of fatigue and sleep. At high doses caffeine stimulates the motor cortex of the brain and interferes with the sleep-wake cycle, causing side effects such as shakiness, anxiety, and insomnia. People’s sensitivity to the adverse effects of caffeine varies, and some people develop side effects at much lower doses. The many effects caffeine has on the brain do not diminish with habitual drinking of caffeinated beverages.\n\nConsuming caffeine in the evening and in the middle of the night will help keep you awake to study for an exam, but it will not enhance your performance on the next day’s test if you do not get enough sleep. Drink caffeinated beverages in moderation at any time of the day or evening to increase alertness if you are not sensitive to caffeine’s adverse effects, but get the recommended amount of sleep. Caffeine has some effects on health that are either promoted or masked by other beneficial chemicals found in coffee and tea. When assessing the benefits and consequences of caffeine intake, take into account how much caffeine comes from coffee and tea versus soft drinks.\n\nThere is scientific evidence that higher consumption of caffeine, mostly in the form of coffee, substantially reduces the risk for developing Type 2 diabetes and Parkinson’s disease. There is a lesser amount of evidence suggesting increased coffee consumption lowers the risk of heart attacks in both men and women, and strokes in women. In smaller population studies, decaffeinated coffee sometimes performs as well as caffeinated coffee, bringing up the hypothesis that beneficial chemicals in coffee other than caffeine may play larger roles in the health benefits of coffee. A review of fifteen epidemiological studies in The Journal of the American Medical Association proposes that habitual coffee consumption reduces the risk of Type 2 diabetes. The risk reduction was 35 percent for those who consumed greater than 6–7 cups of coffee per day and was 28 percent for those who consumed 4–5 cups daily, compared with people who consumed less than 2 cups of coffee per day.\n\nParkinson’s disease is an illness of the central nervous system causing many disorders of movement. Research scientists in Hawai’i found an inverse relationship between caffeine intake and the incidence of Parkinson’s disease. Men who did not consume coffee had a five times more likely chance of Parkinson’s disease than men who consumed more than 3 cups of coffee daily. In this study, other caffeine sources, such as soft drinks and tea, were also associated with a reduced risk of Parkinson’s disease. A review of several studies, published in the Journal of Alzheimer’s Disease, reaffirmed that caffeine intake may reduce the risk of Parkinson’s disease in both men and women. There is also some scientific evidence that drinking coffee is linked to a much lower risk for dementia and Alzheimer’s disease."