I am just coming down from that finals rush that us university students are all so accustomed to. Those long nights of studying and early mornings to keep studying – it gets tiring. A lot of students have a particular molecule to thank for getting them through those long days: caffeine. Whether it’s coffee, or energy drinks, students can be seen anywhere on campus chugging down these caffeinated substances. But how does this particular substance work to keep the students active and awake?

What is Caffeine?

Caffeine is a purine alkaloid, which is a particular type of chemical compound. It is found organically in Coffea arabica and Camellia sinsensis.

Coffea arabicaCamellia sinsensis

Coffea arabica is the source of coffee, while Camellia sinsensis is the source of tea.

How does caffeine affect our systems?

Caffeine can be completely absorbed by the stomach and small intestine within 45 minutes, and it takes around 3 to 4 hours just to remove half of the consumed caffeine from your system.

Caffeine stimulates our central nervous system (CNS), which is composed of our brain and spinal cord. By stimulating the CNS, the caffeine molecules fight against drowsiness and helps keep you alert. It does all of this by preventing a nucleoside, named adenosine (which is found in our DNA!), from binding to its receptors in the brain.

Adenosine usually suppresses the CNS when it binds to its receptors; this leads to general drowsiness. When caffeine binds these receptors, adenosine can no longer interact with the brain receptors which leads to a decrease in drowsiness (or increase in alertness!). Another result of caffeine binding these receptors is the stimulation of other neurotransmitters that also lead to an increase in your ability to concentrate and stay awake. These neurotransmitters include: norepinephrine, dopamine, acetylcholine and serotonin (which will be explored later).

An interesting fact about caffeine is that its half life,which is the time it takes to remove half of the consumed substance from your system, can be shortened by one’s smoking. So if you’re smoking, you’re going to need more caffeine than the average person to get relatively the same jolt of energy.

And that’s a brief summary of caffeine and its effects! Now you know how exactly caffeine works to become your savior through those long nights. Thanks caffeine, on behalf of all of us sleep-deprived students.


Ever get too nervous to step onto a stage and speak in front of an audience? What about getting anxious about an upcoming test? Whether it’s when you think of the future or performing a simple task like driving, we’ve all felt anxious at one point.

What is anxiety and why do you get anxious?

Anxiety is often confused to be the same as fear, but I think it’s important to distinguish one from the other. Fear is your response to a known threat that’s in your surroundings while anxiety is more of a response to an unknown threat or an internal conflict1. We don’t fear the future because we don’t know what is in store for us, but not knowing what will happen can make us anxious. Even though they are caused by different situations, their modes of action in our body are the same.

Getting anxious is simply the flight-or-fight response to an unknown threat and is meant to be a evolutionary response for survival2. Without anxiety or fear, we would probably be reckless and die at a young age as a result.

How do you get anxious?

Fear and anxiety are both emotions regulated by a part of your brain that’s called the amygdala3.

When you’re in a situation that would normally lead to anxiety, such as having an internal conflict, a system known as the locus coeruleus (which is found in the pons), is signalled by the thalamus to release a hormone. This hormone, norepinephrine (NE), targets the amygdala, in addition to other systems.

This causes the amygdala to target another part of the brain (the hypothalamus), which causes the release of cortisolepinephrine (aka adrenaline) and NE to induce the ‘flight-or-fight’ response4. Some cortisol goes back and targets the amygdala, which intensifies the signalling and, therefore, the symptoms1.

The three hormones and the nervous system will target organs like your eyes, heart, sweat glands and bladder and will signal for the pupils of your eyes to dilate, your heart to beat faster, your sweat glands to release more sweat and for your bladder to relax. This relaxation of your bladder results in the likeliness of urinating if you are really anxious or scared. Hence the saying ‘I almost peed myself’.

The general signalling path that results in anxiety.

The general signalling path that results in anxiety and a few symptoms of anxiety.

1. Steimer, Thierry. 2002. The biology of fear & anxiety-related behaviours. Dialogues in Clinical Neuroscience, Vol, 4, No. 3, pp. 225-249.

2. DeMarco, Anthony J. 2009. The biology of fear and anxiety. <; 02 January 2013.

3. Feinstein, J.S., Adolphs, R., Damasio, A., and Tranel, D. 2011. The human amygdala and the induction and experience of fear. Current Biology, Vol. 21, No. 1, pp. 34-38.

4. Layton, Julia.  2005. How fear works. <;  02 January 2013.