By Jenny Lam
When needing to pull that all-nighter for tomorrow’s test or to get an extra boost of energy to survive the day without falling asleep, caffeine remains a popular option for many. It’s readily available in numerous drinks, such as coffee, tea, energy drinks, and more. For some, just one coffee isn't enough; they find that they require increasing amounts of coffee to retain the same levels of alertness and attention over time. Many might wonder if caffeine addiction is actually harmful, but can a caffeine “addiction” even be considered an actual addiction? How do people develop a tolerance to caffeine in the first place?
To answer these questions, one must investigate the relationship between caffeine and adenosine, as well as how caffeine alters brain chemistry to keep people awake. Adenosine consists of an adenine (minus a hydrogen atom) attached to a ribose sugar (minus an OH group) and is naturally created in the body during digestion. Food molecules, such as glucose, are broken down by cellular respiration to generate adenosine triphosphate (ATP) to fuel vital cellular processes in our body. Most of the ATP is hydrolyzed, or broken down, into adenosine diphosphate (ADP), which can then be dephosphorylated (have a phosphate group removed) into adenosine monophosphate (AMP). AMP can be further dephosphorylated into adenosine, which can interact with certain receptors to cause various physiological effects. In the brain, adenosine acts as a central nervous system depressant, binding to receptors to promote drowsiness. Adenosine levels rise during waking hours and can be linked to why people feel more sleepy the longer they stay awake. Essentially, adenosine causes us to feel drowsy and sleepy.