Caffeine dependency is the physiological addiction to caffeine that results from habitual intake of foods that contain caffeine, most notably coffee. Other foods that contain caffeine include sodas, energy drinks, tea and chocolate. Teas vary in caffeine content depending on the type of tea, while most sodas 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 drugs used in treating depression. Caffeine might also increase epinephrine (adrenaline) levels, the hormone that kicks in during the fight or flight response. In short, caffeine is a pick-me-up and in today's fast paced world caffeine dependency is prevalent.
Caffeine staves off drowsiness, provides energy, and can create a euphoric mood that can last for three or four hours. As caffeine dependency grows, however, resistance to the effects of caffeine can result in the need to take in greater amounts to achieve the same stimulating effect. At this stage heavy coffee or energy drink users might experience side effects like indigestion, sleep disorders, nervousness, muscle twitches and irritability.
One of the effects of caffeine dependency is withdrawal when caffeine intake is sharply curbed or abruptly halted. Adenosine contributes to the regulation of blood pressure. Because of the inhibitive effect on the adenosine receptors, the body compensates by making more receptors. When caffeine intake ceases there are essentially too many functional adenosine receptors, which causes dilated blood vessels in the brain resulting in headache and nausea. Given a few days, the body will compensate, producing fewer receptors. Withdrawal can take anywhere from two to five days.
While governments control many stimulants, caffeine remains legal and is reported to be one of the most widely used drugs in the world. It is likely that many people who suffer from the effects of caffeine dependency don’t realize it is the caffeine in their diets that is causing problems. Studies regarding potential benefits and risks of caffeine are varied with mixed results. Most sources agree that moderate levels of caffeine intake (two to three cups of coffer per day) pose no significant health risks to adults. Caffeine is toxic to some domestic pets, however, including dogs, parrots and horses.