Caffeine dependence is the physiological addiction to caffeine that results from the habitual intake of foods containing caffeine, especially coffee. Other foods that contain caffeine include soda, energy drinks, tea, and chocolate. Teas vary in caffeine content depending on the type of tea, while most soft drinks contain about half the caffeine found in a cup of coffee. Energy drinks also vary in caffeine content from amounts less than a cup of coffee to several cups.
Caffeine is a psychoactive stimulant that affects certain neural transmitters in the brain. By binding to adenosine receptors, it acts as an inhibitor, which in turn increases the activity of dopamine neurotransmitters. Dopamine is known to be a mood elevator, key to the design of some medications used to treat depression. Caffeine can also increase levels of epinephrine (adrenaline), the hormone that is activated during the fight or flight response. In short, caffeine is a stimulant and in today's fast-paced world caffeine dependency is prevalent.
Caffeine prevents drowsiness, provides energy, and can create a euphoric mood that can last three to four hours. However, as caffeine dependency grows, resistance to caffeine's effects may result in the need to take larger amounts to achieve the same stimulant effect. At this stage, users of coffee or energy drinks may experience side effects such as indigestion, sleep disturbances, nervousness, muscle twitching, and irritability.
One of the effects of caffeine dependence is abstinence when caffeine intake is abruptly curbed or abruptly stopped. Adenosine contributes to the regulation of blood pressure. Due to the inhibitory effect on adenosine receptors, the body compensates by producing more receptors. When caffeine intake ceases, there are essentially too many functional adenosine receptors, causing blood vessels in the brain to dilate, resulting in headache and nausea. After a few days, the body will compensate, producing fewer receptors. The withdrawal can take from two to five days.
While many stimulants are controlled by governments, caffeine remains legal and is reported to be one of the most widely used drugs in the world. Many people who suffer from the effects of caffeine dependence may not realize that it is the caffeine in their diets that is causing problems. Studies on the potential benefits and risks of caffeine vary with mixed results. Most sources agree that moderate levels of caffeine intake (two to three cups of chestnuts per day) do not pose significant health risks to adults. However, caffeine is toxic to some household pets, including dogs, parrots, and horses.