Editor’s note: This article was originally written in the final weeks of our Spring 2020 semester. At the time of publishing, UC Berkeley is operating fully online, with students scattered across the globe, glued to our laptops for classes, internships, and social lives. In the US, this summer was one of reckoning, with the pandemic, mass protests for racial justice, wildfires, and an unprecedented economic crisis, all of which have brought the nation to its knees. Reading this article again, I can’t help but think about how deeply my own outlook on the world, this field, and my own self has changed since March. It is my hope that through the articles we publish this semester we can all learn more about what it means to be human, and how it brings us together rather than divides us. — Lillian

When Life Gives you Lemons
Friday the 13th of March 2020: a clichéd ominous day turned out to be true for UC Berkeley students, who received the news that their campus activities would be moving online, alongside several of their peers around the nation. Soon afterwards, in-person classes ceased, and within a week or two administrative offices and research operations also stopped. The sudden, abrupt changes in the lives of faculty, staff, employees, and students became a great source of stress. Students would have to learn to study from home, away from friends and the social atmosphere they had grown close to. Faculty would have to completely adapt their curricula to fit the framework of online learning. Added fears of infection by a deadly virus served only to increase the amount of stress all these individuals felt.
And it’s not just Berkeley. Globally, the world entered a state of panic. Mainstream media outlets report that death tolls are climbing into the tens of thousands in the US. The unemployment rate is at levels we haven’t seen since the Great Depression. And while social distancing does help to mitigate infections due to interactions, it also fuels mental anxiety by removing many of our ways of coping with stress and forcing us into unfamiliar atmospheres.

Good Cop

We think of stress as a largely negative thing. Nobody wants to be stressed out; we would all love to live chilled out lives and be our happiest, most relaxed selves all the time. But stress is actually a very important biological response to external stimuli, making it one of the primary reasons that humans have become such a dominant species.

Animals evolved stress responses to keep themselves alive. We like to think of it as a “fight-or-flight” in response to an external threat; we either stand our ground and fight back, or we run away and live to fight another day. Short term stress, which triggers the fight-or-flight response is called acute stress, and is an essential part of life. Within the autonomic nervous system (which primarily controls involuntary action) is the sympathetic branch, the division responsible for controlling the fight-or-flight response. This is one of the reasons why you cannot voluntarily “force” yourself to respond to stressors, your body does this automatically.

The fight-or-flight response is fueled by the neurotransmitter/hormone combination of norepinephrine and epinephrine. Norepinephrine, commonly known as noradrenaline, helps signals propagate through the sympathetic nervous system and stimulate bodily responses, like an elevated pulse. The stress response becomes prolonged when the adrenal glands (small organs that sit on top of the kidneys) release epinephrine directly into the bloodstream. This allows the stress response to be felt more powerfully throughout the body, and it ensures that we are adequately prepared for the entirety of a dangerous situation. In short, stress is here to keep us alive.

Bad Cop
But too much stress is a bad thing. Another hormone, called cortisol, is also produced by the adrenal glands in response to stress. Cortisol production is stimulated by the activation of a stress response element called the HPA axis, which consists of three organs–the hypothalamus, the pituitary gland, and the adrenal glands. The hypothalamus works to maintain homeostasis (equilibrium) within the body, and when stressful elements persist for a long time it stimulates the pituitary gland to produce a chemical called ACTH. ACTH then travels down to the adrenal glands and stimulates cortisol production by the adrenal glands.

Cortisol works in a variety of different ways, but one of the most important consequences of cortisol production is suppression of the immune system. This can be good in periods of acute stress — in emergency situations such as escaping a predator– when you wouldn’t want to develop a fever and feel sick. But when stress is prolonged (chronic stress, as opposed to acute stress), the combined effects of too much epinephrine, norepinephrine, and cortisol in the body cause widespread health issues. Individuals who experience stress over long periods of time are more likely to have high blood pressure, heart disease, diabetes, and weaker immune systems, among many other health problems. So even though COVID-19 is already enough to be fearful of, “cabin fever” is definitely real and can lead to other health concerns.

Another consequence of long term stress exposure occurs in the amygdala, a region of the brain responsible for emotions such as fear, anxiety, and sadness, as well as triggering the stress response by sending distress signals to the hypothalamus. In addition, repeated exposure to stressful stimuli has been shown to permanently alter how the amygdala responds. These changes include the expansion of dendrites — the region of a neuron responsible for receiving signals — and a decline in the production of an inhibitory neurotransmitter called GABA. These changes lead to hyperactivation by making neurons in the amygdala less inhibited. In short, the amygdala becomes trigger-happy, and may contribute to the psychiatric disorders which are associated with stress, which include phobias, panic attacks, anxiety disorders, and PTSD. This may be why many people are reporting a decline in their mental health ever since the start of this pandemic.


During this time of rapid change and increasing uncertainty, we should be paying more attention than ever to the effects that stress can have, and what sources it may come from. For more than a month now, many of us have been socially distancing and staying at home in self-isolation, in attempts to mitigate the spread of a deadly virus. From a public health standpoint, this is absolutely essential–we must continue to do these things in order to ensure we come out of the pandemic as strong as possible. That doesn’t change the fact, though, that quarantine has affected many of our mental states. One of the biggest changes we’ve faced is that normal everyday tasks now have additional risks — which means more stress-inducers. Going out for a walk means avoiding our neighbors at all costs and trips to the grocery store are no longer as benign as they once were. Restaurants which used to be crowded with people are now empty. Many people have doubts about ordering packages online, in fear of residual viral particles remaining on packaging. When evaluating the consequences of so many more decisions, we consequently begin to experience decision fatigue, causing us to make poorer, more irrational choices and experience excess amounts of stress. Biological stress also builds up as a result of social isolation–many individuals are no longer able to meet with their close friends and family because they live far away, and as a result they have lost a significant amount of human contact. Studies indicate that this also causes spikes in cortisol, causing deleterious effects in the long run. Our body clocks have also been thrown into disarray. With the absence of defined work or study routines for a significant portion of the population, as well as college students needing to adjust their sleep schedules as a result of being in a different time zone from their campus, it is no wonder that our sleep schedules are more disturbed now than they used to be. Increased amounts of time spent on electronic devices as students take classes from home and the workforce has to have work related meetings online as well also deregulates our body’s normal sleep schedule, again leading to increases in cortisol and decreased resistance to stress. Confining people to the same environment and preventing in person interaction, while demonstrably positive measures to combat the spread of the virus, also lead to elevated levels of anxiety and depression.

… make Lemonade

It seems like there’s no upside, and there’s no single solution to these problems. But our own biology could be the key to getting rid of stress. Just as we have a natural stress response, we also have a natural “destressing” response, stimulated by the parasympathetic nervous system, the counterpart to the sympathetic system described earlier. The parasympathetic system dials back the effects of the sympathetic, encouraging relaxation and natural bodily functions such as digestion. But to allow the parasympathetic system to do its work, we must find a way to avoid stressful stimuli. Activities such as exercise, regular sleep, and even social interaction in the form of group video calls with friends and family activities within the home, if possible, can help mitigate the stress response and promote relaxation. Picking up a new hobby, reading a book, or learning that language you’ve always wanted to are also great ways to redirect negative mental energy into constructive output. Notably, meditation has been shown to dramatically reduce the biological stress response, so much so that the neurotechnology company Muse has developed EEG headsets to promote meditation and monitor the user's state of mind. Most importantly, we all need to stay on top of our work to the best of our abilities–whether that is schoolwork, or work for a career, or just simple tasks around the house. Set schedules for yourself which include times where you are working, as well as downtime to relax and unwind. Holding yourself accountable for lapses in productivity can actually help as well. All these techniques, and plenty more, help the parasympathetic nervous system activate, leading to reductions in cortisol levels, epinephrine levels, and a gradual adjustment back to normalcy.

COVID-19 put a roadblock in everyone’s lives, and has been a massive source of stress for many, if not all people. By understanding the biology of stress, we are better equipped to handle it. Hopefully, we will be able to come out of this crisis with a greater appreciation for the importance of relaxation during our otherwise hectic lives.

This article was written by Michael Xiong and Sameer Rajesh and was edited by Jandy Le and Lillian Shallow. Michael studies Chemical Biology at UC Berkeley. Sameer is a Biochemistry student in the Molecular and Cell Biology Department at UC Berkeley. Jandy is an Integrative Biology student at UC Berkeley. Lillian studies Microbial Biology at UC Berkeley.

We write on psychology, ethics, neuroscience, and the newest in neural engineering. @UC Berkeley

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