Caffeine's strongest effects are felt in the first hour after consuming it, but some effects can last from 4 to 6 hours. Caffeine causes neural excitation in the brain, which the pituitary gland perceives as an emergency and stimulates the adrenal glands to release adrenaline. Caffeine also increases dopamine levels -- the neurotransmitter that is affected by drugs like amphetamines and heroin. Although this occurs on a much smaller scale than seen in other drugs, this may attribute to caffeine's addictive quality.
While caffeine is mildly addictive, it has not been shown to have a direct link with any serious health risks. Still, anyone who's been up all night after drinking too much coffee can tell you that caffeine can affect a person's mood and sleep pattern. Here are some of the frequent effects of caffeine:
Caffeine is a diuretic. Caffeine prompts the body to lose water through urination. This can lead to dehydration and is the reason that caffeinated drinks are not a good idea when working out or doing other activities that require fluids. In fact, it is suggested that you consume an additional 8 ounces of water for every cup of coffee you drink.
Caffeine can cause you to feel nervousness, restlessness, irritability or anxiety. It can temporarily speed the heart rate and raise blood pressure. If you're feeling stressed out, a cup of coffee can actually exacerbate, rather than help, this feeling. Too much caffeine can also hurt a person's ability to concentrate, making it difficult to study.
Caffeine can cause insomnia. It can be very hard to fall asleep when you consume a lot of caffeine. This is especially true if you consume it at night, but is also true of higher doses consumed earlier in the day.
Some caffeinated beverages can have other health effects. For instance, the acid in coffee can upset the stomach, and worsen ulcers. Coffee consumption has also been linked to a possible increased risk of having elevated blood cholesterol. Additionally, the high quantities of sugar found in caffeinated beverages such as energy drinks and sodas can predispose an individual to diabetes and other related cardio metabolic disorders.
Caffeine can have negative effects on a pregnancy. These effects include an increased risk for difficulty conceiving, low birth weight of babies born to people who consumed moderate amounts of caffeine, and miscarriage. Caffeine is transmitted through the placenta and through breast milk to the baby. Therefore, if you're pregnant or thinking about becoming pregnant, the FDA recommends that you stop consuming caffeine or cut back to 1 cup per day.