The drinking of coffee began approximately 1000 years ago in Arabia and
this custom spread to Europe at some point during the 16th 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 does not include 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.
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) and 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 2 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 1 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 6 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 1 or 2 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.
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