There’s a reason why “sick and tired” just rolls off the tongue—study after study shows that being sick and being tired go hand in hand. Think of exhaustion and illness like some diabolical duo, a Bonnie and Clyde-style assault on your immune system! 

Getting sleep helps the body protect itself against infection. Likewise, being sleep deprived can weaken our immune defenses. You don’t feel on your A-game when you’re pooped…and, similarly, your immune system is struggling when you’re struggling to keep your eyes open.

Here are just a few amazing connections that scientists have found between sleep and avoiding getting sick …

Sleep deprivation suppresses your immune system, making you more susceptible to illness.

Ever notice that you’re especially prone to sniffling, sneezing, and other sickness when you don’t get enough ZZZs? It’s not in your head! 

For example, being sleep deprived makes us more likely to catch a cold. In a 2009 study, people sleeping less than 7 hours per night had a 3 times greater risk of catching a cold than those with 8 hours or more.

A study from the University of Washington dug into the relationship between chronic sleep deprivation and the immune system. By examining 11 identical twins with different sleep patterns, researchers found that the twins who slept less had a more depressed immune system, compared with their siblings. 

We all know that fatigue makes us more cranky and easily inflamed, but it actually undermines a key part of the body’s inflammatory response—called cytokines— absolutely essential for fighting off infections.

And, as exhaustion rises so does the risk of serious infection. In a study of 57,000 women, those trying to get by on less than 5 hours of sleep a night (pretty common for new parents) had a 50% increase in risk of pneumonia.

Sleep helps fight infection and boosts the immune system’s response to vaccinations.

While a lack of sleep potentially weakens your immune defenses, on the flip side, several studies have found that sleep promotes a stronger immune response to vaccines—which improves our body’s immunological memory!

Sleep may also help our T cells (basically the immune system’s attack dog that works specifically against viruses) better glom onto their target to fight the infection, according to a study out of Germany.

Bottom line: Sleep is one of the best things you can do to strengthen your immune system and protect your body from cold and flu…and potentially from more serious illness too!

About Dr. Harvey Karp

Dr. Harvey Karp, one of America’s most trusted pediatricians, is the founder of Happiest Baby and the inventor of the groundbreaking SNOO Smart Sleeper. After years of treating patients in Los Angeles, Dr. Karp vaulted to global prominence with the release of the bestselling Happiest Baby on the Block and Happiest Toddler on the Block. His celebrated books and videos have since become standard pediatric practice, translated into more than 20 languages and have helped millions of parents. Dr. Karp’s landmark methods, including the 5 S’s for soothing babies, guide parents to understand and nurture their children and relieve stressful issues, like new-parent exhaustion, infant crying, and toddler tantrums.

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Disclaimer: The information on our site is NOT medical advice for any specific person or condition. It is only meant as general information. If you have any medical questions and concerns about your child or yourself, please contact your health provider.