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Everyday Habits That Weaken Immunity, Says Science

These mistakes can put you at risk.

The immune system can seem mysterious and conceptual—that invisible force field which protects our bodies from infection by invading viruses and bacteria. Sometimes the force field breaks down, and we get sick; most of the time, it works properly, and we don't give it a second thought. But in the age of COVID, many of us are researching how to improve immunity. Social media is full of ideas, and most of them are snake oil. But solid science tells us there are several things we do every day that can weaken our immune systems; avoid them and you'll keep your body in fighting shape. Read on to find out more—and to ensure your health and the health of others, don't miss these Sure Signs You Have "Long" COVID and May Not Even Know It.


Drinking Too Much Alcohol

Pouring whiskey drink into glass

Experts have known for years that overindulging in alcohol weakens the immune system in a multitude of ways. Drinking too much increases your risk of heart disease, respiratory infections, slow wound healing, sepsis, and more than 10 types of cancer. To avoid that, drink moderately—meaning no more than two drinks a day for men and one for women—or abstain.


Not Getting Enough Sleep

Blond Woman can't sleep at night.

When we sleep, major body systems repair themselves. When you're not getting adequate rest, your heart, brain and immune system aren't getting adequate maintenance. A growing body of research has linked poor-quality sleep to a range of serious illnesses, including cancer, heart disease, and dementia. Experts such as the National Sleep Foundation recommend that adults get seven to nine hours of quality sleep every night.

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Not Getting Enough Vitamin D

vitamin d

Having inadequate blood levels of vitamin D may compromise your immune system. Take it from the nation's top infectious disease expert, Dr. Anthony Fauci, who downs a daily vitamin D supplement. "If you're deficient in vitamin D, that does have an impact on your susceptibility to infection," he said in an interview last fall. "I would not mind recommending—and I do it myself—taking vitamin D supplements. There is good evidence that if you have a low vitamin D level, that you have more of a propensity to get infected when there are infections around."

RELATED: 9 Everyday Habits That Might Lead to Dementia


Being Lonely

Melancholy woman resting at the terrace

COVID has dominated the headlines for the last 18 months, but scientists say we're dealing with a simultaneous "silent epidemic:" Loneliness. Feeling lonely seems to induce a stress response that causes inflammation in the body, potentially impairing the heart, immune system and brain. Studies have found that people who report feeling lonely have a higher risk of cancer, cardiovascular disease, and dementia. To keep your body functioning at its best, make an effort to stay connected to others every day.  

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Constantly Stressing Out

Mature businessman experiencing a headache while working at his desk

"Try to avoid or alleviate severe stress, which we know can sometimes impact the immune system," said Fauci last fall. Chronically being stressed out causes the brain to produce more of the stress hormone cortisol, which has a number of negative physical effects, including weakened immunity. According to the American Cancer Society, people who experience chronic stress are more prone to the common cold and viral infections like the flu. Excess cortisol also tells the body to store fat in the unsightliest—and most dangerous—place: In the belly. And to get through this pandemic at your healthiest, don't miss these 35 Places You're Most Likely to Catch COVID.

Michael Martin
Michael Martin is a New York City-based writer and editor. Read more about Michael