Coffee – the ever-present beverage that serves as the lifeblood for many exhausted workers or a quick wake-me-up drink in the morning. But how does this ever-present drink work at keeping people awake, and what is the science behind it?
At its core, coffee contains a chemical known as caffeine. This substance mimics the substance adenosine in the human body, which promotes sleep and suppresses arousal. Caffeine acts oppositely as it blocks adenosine receptors, stimulating constriction of blood vessels in the brain and making the body feel more awake. However, this effect has consequences to it. When the caffeine is finally broken down, the adenosine in the body floods the receptors and makes the person feel even more exhausted and experience lethargy. Yet the initial effect is what makes caffeine products so beloved by their consumers.
The body can develop tolerance to caffeine, however. It is estimated that with one cup of coffee daily, tolerance to caffeine will be built up within a week to 12 days. This tolerance requires the consumption of more and more caffeine products to achieve the same effect. As caffeine functions like a drug just like any other drug, its users can experience withdrawal symptoms when the daily intake is suddenly stopped. These symptoms such as fatigue, irritability, and headaches can come on between 12 to 24 hours after the last cup. They last for about ten days when the process finally is completed. Hence, to reduce these unpleasant symptoms, people trying to cut down on caffeine should do it gradually with the substitution of decaffeinated or non-caffeinated substances to ward off the worst withdrawal symptoms.