By: Thunuvi Waliwitiya
Have you ever felt anxious about an upcoming exam, worried about a deadline, or encountered a dangerous animal? Well if you have, you know what it’s like to be stressed! We’ve all experienced stress in a variety of forms. Stress can occur as the result of a single, short-termed event or due to recurring exposure to a stressor, otherwise known as as chronic stress. (1) While chronic stress definitely has a fair share of negative impacts on your health, short-term stress can be beneficial and help you get out of sketchy situations!
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You might have heard the term ‘stress’ being tossed around quite casually. However, according to the National Institute of Mental Health, stress is defined as the brain’s response to a variety of demands. (2) Let’s break this down. Our body constantly strives towards homeostasis. A state of homeostasis is present when our body performs optimally under different circumstances, essentially keeping us in a balanced state. When the state of equilibrium is threatened by any stressor, our body employs a mechanisms to protect ourselves and to combat the destabilizing effects of the stressor. (3)`
When you experience a stressful event, sensory information is delivered to the limbic system of the brain, which is comprised of several structures including the hippocampus, amygdala and prefrontal cortex. (3) The hippocampus has an important role in the development of memory and learning- two functions that are crucially important to the stress response. (4) Think of a time where you faced a threat—your hippocampus helped assess the situation! The amygdala, which has a role in emotional processing, also plays a role in the stress response. When the amygdala senses fear and distress, it sends a signal to the hypothalamus which acts as a command centre and communicates with various areas of your body so you can fight, freeze, or flee. This is why you may notice your heart rapidly beating, faster breathing, and a rush of adrenaline when you are stressed. Ultimately, this helps you fight or flee the presence of a stressor!
https://www.simplypsychology.org/limbic-system-structures.jpg?ezimgfmt=rs:380x271/rscb30/ng:webp/ngcb30
To understand why we feel stressed, it is important to understand the mechanism of the hypothalamic-pituitary-adrenal (HPA) axis. This process is responsible for secreting cortisol— a hormone that is helps promotes resistance to stress, from the adrenal gland. Hang in there, it gets a little confusing!
Firstly, the hypothalamus contains specialized cells that create and releases corticotrophin-releasing hormone (CRH). The CRH travels to your anterior pituitary gland which will then secrete adrenocorticotropic Hormone (ACTH). This hormone travels to and acts on the adrenal gland. In response, the adrenal gland secretes cortisol. Cortisol is helpful for our response to stressors as it aids in energizing our body, allowing it to face a challenge. This way, our nervous system can keep firing, keeping us alert, and our skeletal muscle has energy (5).
So far so good right? Stress helps us get out of some scary situations, but what about chronic stress? Aside from the unpleasant feeling you have probably experienced, prolonged stress can produce significant harm to your body and brain. Normally, cortisol levels will return to normal after a stressful event has passed, but high levels of cortisol are produced with chronic stress. Unfortunately, this can wear down the brain’s ability to properly function. Cortisol works by suppressing non-essential functions of the body, as a result the body’s immune system stops functioning. Conseqeuentlially this increases susceptibility to infections and sickness. Research found increased levels of cortisol kills neurons and reduces hippocampal volume. (4,5) Cortisol also has direct effects on memory function; increased levels result in impairments in verbal declarative memory function.
Without a doubt, stress exists in everybody’s life and as such, it’s important to manage stress to mitigate negative effects as mentioned above.
Here are some ways to help reduce stress
Yoga and meditation (6)
Spending time outdoors (7)
Listening to music (8)
Glossary
Homeostasis: a relatively equal state of equilibrium or a tendency towards such a state between the different but interdependent elements or group of elements of an organism.
Neurons: cells of the brain, responsible for receiving sensory input from our surroundings and sending motor commands to our muscles in response
Limbic system: part of the brain that is involved with memory storage as well as behavioural and emotional processes.
Amygdala: region of the brain that is involved with fear response and emotional processess.
Declarative memory: facts and events that can be consciously recalled.
References
5 Things You Should Know About Stress [Internet]. National Institute of Mental Health (NIMH). [cited 2021 Nov 26]. Available from: https://www.nimh.nih.gov/health/publications/stress
The Mind and Mental Health: How Stress Affects the Brain [Internet]. Touro University WorldWide. 2016 [cited 2021 Nov 26]. Available from: https://www.tuw.edu/health/how-stress-affects-the-brain/
de Kloet ER, Joëls M, Holsboer F. Stress and the brain: from adaptation to disease. Nat Rev Neurosci. 2005 Jun;6(6):463–75.
Bremner JD. Does Stress Damage the Brain? BIOL PSYCHIATRY. :9.
Bremner JD. Traumatic stress: effects on the brain. Dialogues Clin Neurosci. 2006 Dec;8(4):445–61.
Thirthalli J, Naveen GH, Rao MG, Varambally S, Christopher R, Gangadhar BN. Cortisol and antidepressant effects of yoga. Indian J Psychiatry. 2013 Jul;55(Suppl 3):S405-408.1.
Lohr VI, Pearson-Mims CH, Goodwin GK. Interior Plants May Improve Worker Productivity and Reduce Stress in a Windowless Environment. Journal of Environmental Horticulture. 1996 Jun 1;14(2):97–100.1.
Normalization of hypertensive responses during ambulatory surgical stress by perioperative music - PubMed [Internet]. [cited 2021 Nov 26]. Available from: https://pubmed.ncbi.nlm.nih.gov/11382277/
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