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You're Stressing Me Out: The Science of Stress

We all have experienced stress in one form or another. Whether you are trying to finish an essay 5 minutes before the deadline, have overslept on the day of that really important early meeting or tried on everything in your wardrobe and still got nothing to wear, stress can take over your entire being and leave you feeling flustered and helpless. But what actually happens to your insides when you have a stressed-out episode? Those cries of frustration and sudden waves of anger are mediated by alterations to specific hormones in your brain and body, and your genetics, environment and development determine how well you can cope with these fluctuations. Even though no-one enjoys being stressed out, there are important reasons why evolution has selected for this response. However, dysregulation of these internal pathways can result in an inhibiting prolonged state of stress and ill-health.

Why am I so stressed? The reasons for the stress response

‘I wish I didn’t get so stressed about things’: a common thought following a period of worry and tension. Sometimes you may feel like you have worked yourself up over nothing, or other times you wish you could be one of those easy-going people who lets straining situations pass them by. All traits we possess have been selected for over thousands of years, and stress is no exception.

The organ systems in your body are finely-tuned to be in a balanced state and when this state is threatened, energy from other ‘maintenance’ activities is redirected to prepare to fight off the disruption. Long-term processes such as growth, reproduction, digestion and immunity are put on hold, so your body can use existing energy from these systems to generate even more energy to evade the stress. Your body increases your heart rate and blood pressure, your breathing rate goes up and there is activation of your colon to absorb as much existing scran as possible to increase energy levels. This translates to you feeling more alert, having better cognition and more focused attention to combat that threat to your internal harmony.

Over your lifetime, there are periods when you are more vulnerable to stress. As an infant all the way through to late adolescence, your stress response is much more plastic so experiences faced in early life shape how you respond as an adult. You may reflect on your youth with a wistful haze as a period when life wasn’t so stressful and looking back on your teenage years, you may have blissfully forgotten how much of a moody tyrant you were. In the adolescent body, the stress response is heightened, leading to you absolutely losing it when you were asked what you wanted for breakfast. The chemicals responsible for your stress response are actually pretty similar in their levels in the teenage and adult body, but the amount of times they are released and the duration of this release which is increased in teenagers, meaning those meltdowns are inevitable (sorry parents).

Genetically, you can be more inclined to be stressed than others. This is because stress is controlled by proteins encoded by genes. If you have any variation in your genes which leads to higher expression of these proteins, you will be more sensitive to stress whereas if you have lower levels, you are much more likely to be laid back. Environment can alter your response to stress, especially at a young age; with toxic early stressors leading to increased sensitivity to stress later on in life. Also, if you associate a specific environment with being stressed (like the office at work), your response may be more heightened in this environment than say in a spa hotel lounging by the pool. The psychological aspect to stress is huge and trying to take your mind off it can sometimes be the best medicine.

Should I stay or should I go? The Chemicals important for Stress

It may come as no surprise to you that stress is regulated by hormones; the chemical messengers responsible for those out-of-the-blue mood swings and emotional breakdowns watching The Simpsons Movie (yes, I cried at that. Yes, I was 15 and hormonal. Yes, I would still probably cry at that because even though I am 26, I am an emotional wreck). There are two hormonal responses to an incoming stressor; one rapid and one slow. The rapid response is responsible for generating the feelings we associate with being stressed; increased heart rate, trouble breathing, sweating and many more unpleasantries. All of these bodily functions are under control of the sympathetic nervous system and they are activated by the hormone adrenaline. We have all heard of adrenaline and how it makes you jittery and full of energy. This hormone is evolutions answer to being in the final round of a game show when you have the option of taking the money or risking your prize for an even bigger jackpot. Adrenaline causes the ‘fight or flight’ response, which is important in physically getting your body out of a stressful situation; whether that be to stay and fight the stressor or to run to the hills and never return. This hormone is also called epinep

hrine and the levels of it in the blood alter the actions of the sympathetic nervous system; with high levels leaving your heart is pounding and blood pressure soaring. These actions all increase the amount of energy available for you to scrap or bomb it.

The main hormone in the slow response to stress is cortisol. This is a type of steroid (glucocorticoid) which acts to increase blood sugar, supress inflammation and enhance cognitive function like memory. This aspect of the stress response is important for your body to maintain its heighten state if needed, increase anti-inflammatory signalling and remember exactly what you did so if faced with the same stressor again, you can reuse that info. If you have ever been put in a situation which causes high stress, I bet you can remember almost every second of that experience. But if I asked you how your day was last Tuesday at work, hours of time blur into one as nothing of note happened (unless a tiger jumped through your window last Tuesday at work, in which case, the former situation applies). Cortisol also has the super important job of stopping you feeling stressed. As confusing as this may sound, cortisol acts on the brain region responsible for the stress response (keep reading for more on this) and turns it off. This is an extremely important job as otherwise, you would constantly be stressed. When something generated by a system is also responsible for switching it off, it is called a negative feedback loop.

My head’s up the wall: The Brain to Body Stress Pathway

Now we know about the hormones responsible for the symptoms of stress, it is important we understand how they come to be swimming around in our blood. If you come face-to-face with a lion, how does your body know to be stressed? You may love lions and think they are really cute on a David Attenborough docu but if one was growling in your face in real life, it is quite important you can spring into action and get outta there. Your senses, such as sight and sound, as well as memories and associations infiltrate your brain and if the brain deems this combination of signals to scream ‘stress’, an area of the brain called the hypothalamus is activated. The hypothalamus is a small but very well-connected region at the base of the brain and contains neurons which release many different hormones. The main hormone released by the hypothalamus which turns on your stress response is corticotropin-releasing hormone (CRH), and this ‘on’ switch is boosted by another hormone called arginine vasopressin (AVP). Basically, CRH acts like turning on a dimmer switch light in a dark room, letting you clearly see your surroundings. When AVP is released, this is like turning that dimmer switch up to full brightness; letting you see every detail that room has to offer. This signalling system gives variation to the stress response. It would be pretty bad if a small stress like your shoe lace coming undone in a busy station lead to a full-blown meltdown so varying the levels of both hormones gives a spectrum of responses. The way these two hormones work together is called synergy.

These two hormones are part of a system called the Hypothalamic-Pituitary-Adrenal Axis (HPA); a fairly complex arrangement linking the hypothalamus to the pituitary gland and the adrenal glands. The pituitary gland is a very small organ also found at the base of the brain responsible for hormone production and is termed the ‘master gland’ as it can activate all the other glands in the body. Of these glands exists the adrenal glands; based far away from the brain, just above the kidney. The adrenal glands are responsible for producing hormones vital for human survival and this is where your good friend’s adrenaline and cortisol are produced and released into the blood stream. On your average day, the pituitary gland signals to the adrenal glands to release these and other hormones in a rhythmic cycle so our bodies can function correctly but are not in complete hormonal overload 24/8.

When you are faced with a stressful situation, the brain alerts the hypothalamus to ramp up the release CRH and AVP. This in turn leads to an enlarged stimulation of the pituitary gland, with an increased release of adrenocorticotropic hormone (ACTH). The action of this hormone is given away by its name; it acts to stimulate the adrenal glands and lets it pump out adrenaline and cortisol to initiate the physical alterations needed to combat stress. As mentioned before, cortisol acts directly on the hypothalamus to switch off the release of CRH and AVP and therefore, shuts down the entire stress response. If this response is not stopped, serious health conditions such as depression, sustained anxiety, infertility, reduced growth, heart problems and issues with immunity can kick in. The severity of these illness shows us how important proper regulation of stress is and why it is important to destress. This can be done through mediation, taking a break (fellow students!), exercise and practicing a hobby. This can help literally take your mind off the stress and reduce hypothalamic signalling – the mind is a bloody powerful thing.




When you are next feeling stressed, try to think about how the system works. Yes, your heart may be pounding and your appetite is out the window but thankfully, this response is made to be switched off. If you are experiencing chronic stress, talk to your GP and put yourself first as it really can cause damage. My advice is to get yourself to that beach in Bali, drink cocktails and chill. Your body needs it.

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