I’m feeling run down. Why am I more likely to get sick? And how can I boost my immune system?
<div class="theconversation-article-body">
<p><em><a href="https://theconversation.com/profiles/sathana-dushyanthen-1169328">Sathana Dushyanthen</a>, <a href="https://theconversation.com/institutions/the-university-of-melbourne-722">The University of Melbourne</a></em></p>
<p>It has been a long winter, filled with many viruses and cost-of-living pressures, on top of the usual mix of work, study, life admin and caring responsibilities.</p>
<p>Stress is an inevitable part of life. In short bursts, our stress response has evolved as a survival mechanism to help us be more alert in <a href="https://theconversation.com/no-you-cant-blame-all-your-health-issues-on-high-cortisol-heres-how-the-hormone-works-203162">fight or flight situations</a>.</p>
<p>But when stress is chronic, it weakens the immune system and makes us more vulnerable to illnesses such as the <a href="https://www.healthline.com/health/can-stress-make-you-sick#:%7E:text=The%20common%20cold&text=Inflammation%20has%20been%20linked%20to,to%20the%20cold%2Dcausing%20germs.">common cold</a>, <a href="https://journals.lww.com/psychosomaticmedicine/abstract/1999/03000/psychological_stress,_cytokine_production,_and.9.aspx">flu</a> and <a href="https://onlinelibrary.wiley.com/doi/abs/10.1002/smi.3017">COVID</a>.</p>
<h2>Stress makes it harder to fight off viruses</h2>
<p>When the immune system starts to break down, a virus that would normally have been under control starts to flourish.</p>
<p>Once you begin to feel sick, the <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4465119/">stress response</a> rises, making it harder for the immune system to fight off the disease. You may be sick more often and for longer periods of time, without enough immune cells primed and ready to <a href="https://link.springer.com/chapter/10.1007/978-3-030-16996-1_6">fight</a>.</p>
<p>In the 1990s, American psychology professor Sheldon Cohen and his colleagues conducted a number of <a href="https://www.cmu.edu/common-cold-project/">studies</a> where healthy people were exposed to an upper respiratory infection, through drops of virus placed directly into their <a href="https://www.nejm.org/doi/full/10.1056/NEJM199108293250903">nose</a>.</p>
<p>These participants were then quarantined in a hotel and monitored closely to determine who became <a href="https://theconversation.com/stress-less-it-might-protect-you-from-covid-153361">ill</a>.</p>
<p>One of the most important factors predicting who got sick was prolonged psychological <a href="https://journals.sagepub.com/doi/full/10.1177/1745691620942516">stress</a>.</p>
<h2>Cortisol suppresses immunity</h2>
<p>“Short-term stress” is stress that lasts for a period of minutes to hours, while “chronic stress” persists for several hours per day for <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5964013/#:%7E:text=Therefore%2C%20a%20major%20distinguishing%20characteristic,weeks%20or%20months%20%5B9%5D.">weeks or months</a>.</p>
<p>When faced with a perceived threat, psychological or physical, the hypothalamus region of the brain sets off an alarm system. This signals the release of a surge of hormones, including adrenaline and <a href="https://www.embopress.org/doi/full/10.15252/msb.20209510">cortisol</a>.</p>
<figure class="align-center "><img src="https://images.theconversation.com/files/616892/original/file-20240903-18-blrqoz.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px" srcset="https://images.theconversation.com/files/616892/original/file-20240903-18-blrqoz.png?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=472&fit=crop&dpr=1 600w, https://images.theconversation.com/files/616892/original/file-20240903-18-blrqoz.png?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=472&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/616892/original/file-20240903-18-blrqoz.png?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=472&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/616892/original/file-20240903-18-blrqoz.png?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=593&fit=crop&dpr=1 754w, https://images.theconversation.com/files/616892/original/file-20240903-18-blrqoz.png?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=593&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/616892/original/file-20240903-18-blrqoz.png?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=593&fit=crop&dpr=3 2262w" alt="Human brain illustration" /><figcaption><span class="caption">The hypothalamus sets off an alarm system in response to a real or perceived threat.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/hypothalamus-causes-vasoconstriction-illustration-medical-brain-435142264">stefan3andrei/Shutterstock</a></span></figcaption></figure>
<p>In a typical stress response, <a href="https://www.sciencedirect.com/science/article/abs/pii/S147149060300173X">cortisol levels</a> quickly increase when stress occurs, and then rapidly drop back to normal once the stress has subsided. In the short term, cortisol suppresses inflammation, to ensure the body has enough energy available to respond to an <a href="https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2019.00245/full">immediate threat</a>.</p>
<p>But in the longer term, chronic stress can be harmful. A Harvard University study <a href="https://jamanetwork.com/journals/jamapsychiatry/fullarticle/2796097">from 2022</a> showed that people suffering from psychological distress in the lead up to their COVID infection had a greater chance of experiencing long COVID. They <a href="https://jamanetwork.com/journals/jamapsychiatry/fullarticle/2796097">classified</a> this distress as depression, probable anxiety, perceived stress, worry about COVID and loneliness.</p>
<p>Those suffering distress had close to a <a href="https://jamanetwork.com/journals/jamapsychiatry/fullarticle/2796097">50% greater risk</a> of long COVID compared to other <a href="https://theconversation.com/being-stressed-out-before-you-get-covid-increases-your-chances-of-long-covid-heres-why-190649">participants</a>. Cortisol has been shown to be high in the most severe cases of <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7102614/">COVID</a>.</p>
<h2>Stress causes inflammation</h2>
<p><a href="https://stories.uq.edu.au/imb/the-edge/inflammation/what-is-inflammation/index.html">Inflammation</a> is a short-term reaction to an injury or infection. It is responsible for trafficking immune cells in your body so the right cells are present in the right locations at the right times and at the right <a href="https://link.springer.com/article/10.1007/s12026-014-8517-0">levels</a>.</p>
<p>The immune cells also store a memory of that threat to respond faster and more effectively the next <a href="https://theconversation.com/being-stressed-out-before-you-get-covid-increases-your-chances-of-long-covid-heres-why-190649">time</a>.</p>
<p>Initially, circulating immune cells detect and flock to the site of <a href="https://www.nature.com/articles/ni1275">infection</a>. Messenger proteins, known as pro-inflammatory cytokines, are released by immune cells, to signal the danger and recruit help, and our immune system responds to neutralise the <a href="https://stories.uq.edu.au/imb/the-edge/inflammation/what-is-inflammation/index.html">threat</a>.</p>
<p>During this response to the infection, if the immune system produces too much of these inflammatory chemicals, it can trigger symptoms such as nasal congestion and runny <a href="https://journals.sagepub.com/doi/full/10.1177/1745691620942516">nose</a>.</p>
<h2>What about chronic stress?</h2>
<p>Chronic stress causes persistently high cortisol secretion, which remains high even in the absence of an immediate <a href="https://theconversation.com/no-you-cant-blame-all-your-health-issues-on-high-cortisol-heres-how-the-hormone-works-203162">stressor</a>.</p>
<p>The immune system becomes desensitised and unresponsive to this <a href="https://www.sciencedirect.com/science/article/abs/pii/S1043661816307435">cortisol suppression</a>, increasing low-grade “silent” inflammation and the production of pro-inflammatory cytokines (the messenger proteins).</p>
<p>Immune cells become exhausted and start to <a href="https://www.fxmedicine.com.au/blog-post/adrenal-immune-connection">malfunction</a>. The body loses the ability to turn down the inflammatory <a href="https://journals.sagepub.com/doi/full/10.1177/1745691620942516">response</a>.</p>
<p>Over time, the immune system changes the way it responds by reprogramming to a “<a href="https://www.unimelb.edu.au/newsroom/news/2021/april/how-stress-can-stop-immune-cells-in-their-tracks">low surveillance mode</a>”. The immune system misses early opportunities to destroy threats, and the process of recovery can take <a href="https://theconversation.com/being-stressed-out-before-you-get-covid-increases-your-chances-of-long-covid-heres-why-190649">longer</a>.</p>
<h2>So how can you manage your stress?</h2>
<p>We can actively strengthen our immunity and natural defences by managing our <a href="https://theconversation.com/stuck-in-fight-or-flight-mode-5-ways-to-complete-the-stress-cycle-and-avoid-burnout-or-depression-218599">stress levels</a>. Rather than letting stress build up, try to address it early and frequently by:</p>
<p><strong>1) Getting enough sleep</strong></p>
<p>Getting enough sleep reduces <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3132857/">cortisol levels</a> and inflammation. During sleep, the immune system <a href="https://link.springer.com/chapter/10.1007/978-1-4939-6578-6_12">releases</a> <a href="https://theconversation.com/sleep-wont-cure-the-coronavirus-but-it-can-help-our-bodies-fight-it-134674">cytokines</a>, which help fight infections and inflammation.</p>
<p><strong>2) Taking regular exercise</strong></p>
<p>Exercising helps the lymphatic system (which balances bodily fluids as part of the immune system) circulate and allows immune cells to monitor for threats, while sweating flushes <a href="https://www.healthline.com/nutrition/does-exercise-boost-immune-system">toxins</a>. Physical activity also lowers stress hormone levels through the release of positive brain <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7387807/">signals</a>.</p>
<p><strong>3) Eating a healthy diet</strong></p>
<p>Ensuring your diet contains enough nutrients – such as the B vitamins, and the full breadth of minerals like magnesium, iron and zinc – during times of stress has a positive impact on overall stress <a href="https://www.ncbi.nlm.nih.gov/pubmed/22782571">levels</a>. Staying hydrated helps the body to flush out <a href="https://theconversation.com/a-strong-immune-system-helps-ward-off-colds-and-flus-but-its-not-the-only-factor-99512">toxins</a>.</p>
<p><strong>4) Socialising and practising meditation or mindfulness</strong></p>
<p>These activities increase endorphins and serotonin, which improve mood and have <a href="https://www.sciencedirect.com/science/article/pii/S2949834123000351">anti-inflammatory effects</a>. Breathing exercises and meditation stimulate the parasympathetic nervous system, which calms down our stress responses so we can “reset” and reduce <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4940234/">cortisol levels</a>.<!-- Below is The Conversation's page counter tag. Please DO NOT REMOVE. --><img style="border: none !important; box-shadow: none !important; margin: 0 !important; max-height: 1px !important; max-width: 1px !important; min-height: 1px !important; min-width: 1px !important; opacity: 0 !important; outline: none !important; padding: 0 !important;" src="https://counter.theconversation.com/content/237456/count.gif?distributor=republish-lightbox-basic" alt="The Conversation" width="1" height="1" /><!-- End of code. If you don't see any code above, please get new code from the Advanced tab after you click the republish button. The page counter does not collect any personal data. More info: https://theconversation.com/republishing-guidelines --></p>
<p><em><a href="https://theconversation.com/profiles/sathana-dushyanthen-1169328">Sathana Dushyanthen</a>, Academic Specialist & Lecturer in Cancer Sciences & Digital Health| Superstar of STEM| Science Communicator, <a href="https://theconversation.com/institutions/the-university-of-melbourne-722">The University of Melbourne</a></em></p>
<p><em>Image credits: Shutterstock </em></p>
<p><em>This article is republished from <a href="https://theconversation.com">The Conversation</a> under a Creative Commons license. Read the <a href="https://theconversation.com/im-feeling-run-down-why-am-i-more-likely-to-get-sick-and-how-can-i-boost-my-immune-system-237456">original article</a>.</em></p>
</div>
