Coffee: Revision Fuel?

By Georgia Cook (from Issue 2)

9 AM lectures. I wouldn’t stand a chance of making it through them without a cup of coffee. I probably wouldn’t make it through 2 PM lectures either. But all this coffee has me thinking… is this good for me?

The drinking of coffee began approximately 1.000 years ago in Arabia and this custom spread to Europe at some point during the sixteenth century. Before this, unsanitary water conditions drove Europeans to drinking weak beer or wine in order to hydrate – we can all imagine the potential result of that, and it is not exactly conductive to a good work ethic. At the time, the arrival of coffee was considered nothing short of a miracle: simultaneously increasing energy, work ethic and hydration. Only recently have we begun to investigate the effects that coffee has on our bodies.

Coffee contains a molecule called caffeine. Caffeine is very similar in structure to adenosine, a component of adenosine triphosphate (ATP, our bodies’ source of energy). According to Brain Research Reviews, this means that caffeine is able to bind to adenosine receptors in the nervous system. Caffeine is unable to activate these receptors, but blocks the binding of adenosine. Adenosine typically binds to type 2 adenosine (A2) receptors in order to evoke sleepiness and signal to the body that it is time to rest. This explains the alertness associated with coffee consumption: the caffeine in coffee is keeping us from feeling sleepy.

Caffeine also stimulates noradrenaline neurons, resulting in the release of dopamine, associated with euphoria and concentration. However, the effects of caffeine only last for 2-4 hours depending on an individual’s metabolism, which is primarily determined by genetics.

Book opened on a table with two coffee cups next to it
Photo by Timothy Barlin on Unsplash

It is possible to develop a caffeine tolerance in chronic coffee drinkers. Individuals that develop a caffeine tolerance will need to drink more and more cups of coffee a day in order to achieve the same alertness that they would have originally achieved by drinking one cup. This may be due to the plasticity of neurons, resulting in an increased synthesis of adenosine receptors to compensate for the caffeine antagonism.

This creates a vicious cycle, wherein more caffeine is needed to block the binding of adenosine to the newly synthesised receptors. When a chronic coffee drinker then ceases coffee consumption, the high abundance of available adenosine receptors leads to intensified sleep inducing effects. This explains many of the withdrawal symptoms that are associated with coffee, which will be discussed later.

There are many rumours surrounding caffeine consumption and many have proved to be misconceptions. The strongest belief surrounding caffeine (specifically coffee, in my case) is that it is addictive. According to the European Food Information Council (EUFIC), caffeine is a stimulant of the central nervous system (CNS), so regular consumption can lead to mild physical dependence.

Despite this, caffeine is not considered a threat to physical, social or economic health in the same way that recreational drugs such as cannabis or cocaine are. Admittedly, the economic health of chronic coffee drinkers is disputable when considering the cost of visiting London coffee shops. However, similarly to recreational drugs, “coffee addicts” will indeed experience a few withdrawal symptoms.

The reason for this is that the effects of caffeine only persist for 2-4 hours, resulting in the aforementioned vicious cycle leading to caffeine tolerance.

The side effects may last for up to a day (maybe more, particularly if you have more than two cups of coffee a day) and include:

  • Headache
  • Fatigue
  • Anxiety
  • Irritability
  • Depressed mood
  • Difficulty concentrating

None of the above sound very appealing – especially during exam period, the time when students typically consume the most coffee. So I guess we either keep drinking coffee to avoid withdrawal or don’t drink it at all…

But are there any benefits to drinking coffee? Many coffee drinkers will claim that coffee improves their alertness, concentration, energy, clear-headedness and feelings of sociability. However, very few of the alleged effects of coffee are verified by research in the field.

In 1993, Smith et al. demonstrated that consumption of caffeinated drinks had a beneficial effect on alertness and improved performance in a variety of tasks, both during the day and at night. In 1994, the National Academy of Sciences investigated potential performance-enhancing food components, including caffeine. They demonstrated that caffeine is effective in reversing the performance degradations and alterations in mood and alertness observed in individuals suffering from prolonged sleep deprivation. This was concluded to be a long-lasting effect that was not accompanied by any physiological or psychological side effects. Thus, it would seem that there is evidence to support that the primary desirable effects that lure individuals to drink coffee will, in fact, be achieved upon its consumption.

Caffeine may have been demonstrated to reverse the effects of sleep deprivation, but if caffeine is preventing us from feeling sleepy… surely this could lead to a period of secondary insomnia? As caffeine is processed in the liver, it has a short half-life of approximately 5-7 hours. Therefore, for most people one coffee in the morning will not interfere with their sleep cycle. However, how many students do you know that stick to one coffee per day? And only in the morning?

Drake et al. recommends having six coffee-free hours before bed. The basis of this recommendation arose from their research in 2013, in which they demonstrated significant sleep disturbance as a consequence of moderate doses of coffee 3 and 6 hours prior to bedtime. However, this may vary as an individual’s sensitivity to caffeine depends on their metabolism and the number of coffees that they typically consume per day. If an individual has a slow metabolism, it follows that they are likely to be more sensitive to caffeine. Furthermore, the more sensitive they are to caffeine, the more chance there is that they will experience the undesirable side effects associated with it, such as insomnia, nervousness and gastrointestinal tract upset.

So with exams approaching, the primary concern is what will help students’ concentration the most during this period? Coffee? Or simply a good night’s sleep? You’re probably thinking “Oh god, how am I to make it through exams without coffee?!”

Perhaps we can defend our caffeine intake with research conducted by Solfrizzi et al. in 2015. They demonstrated that caffeine may reduce the incidence of mild cognitive impairment, such as dementia, when an individual habitually consumes one or two cups a day throughout life. So there we have it, short and long-term benefits of coffee consumption… who can argue with that?

Most importantly though – drink coffee to enjoy it. If you don’t enjoy it, you can probably live without it.

Leave a Reply