Poor Sleep, Stuffy Air, and Beyond: Which Factors May Contribute to COVID-19 Susceptibility?

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“Zip your coat up or you’ll get sick!”

“Don’t stay cooped up! It’s not good for your immune system.”

You’ve likely received plenty of advice since childhood on how to avoid getting sick — but if you’re immunocompromised in the COVID-19 era, these little warnings can suddenly feel much more pressing.

Of course, not every piece of advice has merit, especially when it comes to something as complex as your immune system. Even researchers are still learning about what boosts or hampers immunity. Nevertheless, if you have a compromised immune system due to an underlying condition or medications that you take, it’s essential to be particularly vigilant in protecting yourself (and others) from infection.

“Being immunocompromised means that you have a weakened immune system, and therefore, you’re more susceptible to several conditions, including COVID-19,” says Christine Kingsley, APRN, Health and Wellness Director of the Lung Institute, who has cared for COVID-19 patients as a nurse.

So, pieces of advice actually have merit? Here are four common warnings that are genuinely effective in avoiding disease.

Eat healthier to boost your immune system.

While some labels may want you to believe otherwise, there is no magic bullet or mushroom elixir for avoiding illness. However, consistently consuming an unhealthy diet can hamper your immune system’s ability to fight off germs.

“A diet that consists of highly processed foods, including refined grains, deli meats, cookies, and chips, is known to weaken your immune system,” says Kingsley. “Poor diets may drive inflammation and cause bacterial imbalance in your gut, which can negatively affect your immunity.”

Although vitamin C is most famously associated with immunity, your immune system is complex and influenced by a network of factors — not just by diet — and certainly not by just one vitamin or mineral. However, malnutrition can impair the production and activity of immune cells and antibodies, according to the Harvard T.H. Chan School of Public Health.

Aim to eat a balanced diet with whole fruits, vegetables, lean proteins, whole grains, and plenty of water. If you cannot readily access this type of diet, a multivitamin may help you avoid malnutrition. “I don’t think we’ve found that [vitamin supplementation] makes a significant difference, but ensuring that any deficiencies are corrected may be beneficial,” says Stuart Campbell Ray, MD, Professor of Medicine and Vice Chair of Medicine for Data Integrity and Analytics in the Department of Medicine at Johns Hopkins Medicine.

In addition to this, a nutritious diet can help you maintain a healthy weight. Excess weight is associated with chronic inflammation because fat tissue generates adipocytokines that can trigger inflammatory processes. Although further research is required, obesity has been identified as an independent risk factor for the influenza virus, which may be due to T-cell impairment (a type of white blood cell), according to the Harvard T.H. Chan School of Public Health.

“It’s essential to consider what truly brings you joy and helps with stress,” says Dr. Ray. “We have a lot of evidence that stress has an impact on immunity, so there is a clear benefit to attempting to manage stress and finding things that are rewarding to you.”

Even if you’re cautious about how often you attend group gatherings and other events, you can still engage in activities at home such as meditation and yoga to help you manage chronic stress. For additional resources, read more about arthritis, mental health, and COVID-19.

You’re getting sick because you’re stressed out.

It may feel like it’s mostly mental, but stress has an impact on the rest of your body as well.

“Stress can cause your immune system to generate an inflammatory response, making you more susceptible to infections and viruses,” says Kingsley. “Stress also raises cortisol levels. Elevated cortisol levels can lead to the suppression of your immune system by reducing the production of white blood cells in your body.”

In particular, stress decreases your body’s lymphocytes, the white blood cells that help you fight infection, according to the Cleveland Clinic. The lower your lymphocyte level, the higher your risk for viruses, and the longer it takes your body to fight them.

“It’s important to consider what really gives you joy and helps with stress,” says Dr. Ray. “We have a lot of evidence that stress has an impact on immunity, so there is some clear benefit to trying to manage stress and finding things that are rewarding to you.”

Even if you’re cautious about how often you attend group gatherings and other events, you can still engage in activities at home like meditation and yoga to help you manage chronic stress. For additional resources, read more about arthritis, mental health, and COVID-19.

Too little sleep will wreck your immune system.

When you catch enough sweet z’s, you don’t just feel better — your immune system operates better, too.

“When you sleep, your immune system releases proteins called cytokines,” says Kingsley. “Cytokines influence the growth of all blood cells and other cells that aid your body’s immune responses. Without sufficient sleep, the production of cytokines may decrease, resulting in fewer antibodies.”

Not only does research indicate that people who don’t get enough quality sleep are more likely to fall sick after exposure to a virus, but a lack of sleep can also affect how quickly you recover if you do become sick, according to the Mayo Clinic.

“When we look at research, people with poorer sleep quality were much more susceptible to infection,” says Dr. Ray. “The worse their sleep quality, the worse their susceptibility was, so there’s a strong correlation.”

In a meta-analysis published in the journal Current Biology, researchers discovered that individuals who get more sleep at night produce a higher level of antibodies that can enhance the effectiveness of vaccines. Getting too little sleep (less than six hours per night) was linked to a substantial decrease in antibody response, especially in men, which is similar to the decline in COVID-19 vaccine antibodies over two months.

Remember: Adults require seven to eight hours of quality sleep every night. If you’re getting less than this, it could affect your immune system or the effectiveness of your recent vaccines.

You need fresh air — being cooped up isn’t good for you.

Getting outside alone may not have an impact on your immune system. “Lack of sun or fresh air are not factors in someone’s susceptibility that I am aware of,” says Norman B. Gaylis MD, FACP, MACR, a rheumatologist based in Aventura, Fla.

That said, SARS-CoV-2 viral particles spread between people more readily indoors than outdoors, where even a breeze can quickly reduce concentrations, per the U.S. Centers for Disease Control and Prevention. Plus, getting outside may make you feel happier and reduce your stress levels, which can be beneficial for your immunity.

It’s also possible that soaking up the sunshine could bolster your immune system, even though more research is needed. Patients with a “likely deficient” vitamin D status had nearly double the likelihood of testing positive for COVID-19 compared to those with a “likely sufficient” vitamin D status, per a 2020 study on a single testing center published in the journal JAMA Network Open. (Read more about the potential link between COVID-19 and vitamin D.)

“We know that people who have more susceptibility to COVID-19, and particularly severe COVID-19, have lower vitamin D levels,” says Dr. Ray. “What we don’t know is whether that link is causal. People with low vitamin D levels also tend to be vulnerable in other ways — they’re often people of color, people of low socioeconomic status, and have other risk factors.”

It’s also not just about being indoors versus outdoors. The quality of the air matters: Environmental factors can hamper your ability to fight off infection, especially when it comes to PM2.5, particles in the air that are 2.5 microns or less in diameter.

“These are tiny particles that are generated with indoor cooking and traffic — especially near freeways,” says Dr. Ray. “There’s good evidence that people who live in high PM2.5 environments are more susceptible to chronic lung disease and probably to respiratory infections.”

To avoid exposure to particle pollutants indoors, you can take measures such as the following, per the California Air Resources Board:

• Use exhaust fans that vent to the outdoors when cooking
• Don’t allow smoking in your home
• Use an electric or gas heater rather than a wood stove or fireplace (if you burn wood, use “seasoned” dry wood and make sure your fireplace or woodstove drafts properly)
• Limit the burning of candles and incense indoors
• Avoid air fresheners, cleaning products, and fragrances that have a pine or citrus scent, since these can react with ozone to form particles and formaldehyde

And of course, while eating healthy, reducing stress, getting enough sleep, and considering air ventilation and quality may help bolster your overall immune system, the most important thing you can do to avoid COVID-19 infection is to get vaccinated (and stay up-to-date with your boosters). Even if you’ve already recovered from a COVID-19 infection, the vaccine provides added protection against the virus, per the CDC.

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