Nightly Rest, Daily Defense: How Sleep Supports Your Immune System

Nightly Rest, Daily Defense: How Sleep Supports Your Immune System

Did you know that sleeping less than 7 hours per night makes you nearly three times more likely to be infected by the common cold than people who sleep 8 hours or more [1]?  

Did you know that women who sleep less than 5 hours per night are almost 70% more likely to get pneumonia than people who sleep 8 hours per night [2]? 

The data are overwhelmingly clear: The quantity and quality of your sleep powerfully influence the function of your immune defenses, which are required to protect you from illness and disease. 

Sleep Deprivation Weakens Immune Defenses 

Deep, restful sleep is essential for the release of cytokines, molecules which regulate your immune system and fight off infections [3]. Conversely, poor sleep quality – whatever the cause – can reduce cytokine production and leave you more susceptible to illness. 

Multiple studies have confirmed this connection. In a classic study, researchers deprived a group of healthy people to 4 hours of sleep for a single night, and found a whopping 70% reduction in natural killer cells, a type of immune cell responsible for preventing the spread of tumors and a diverse range of other pathogens [4]. 

This suggests that – unfortunately – just one night of poor sleep is enough to produce an alarming state of immune deficiency. 

Sleep Deprivation Linked to Systemic Inflammation 

Chronic sleep deprivation has also been linked to increased levels of inflammation, which can impair the immune system's ability to fight off illness. A study conducted on medical residents (who are notoriously sleep deprived) found that those who worked extended shifts and had disrupted sleep had increased levels of inflammatory markers compared to those who had adequate sleep [5]. 

Behavioral Strategies to Improve Sleep and Strengthen Immunity 

These statistics may sound grim, but the good news is that there are simple, actionable steps that everyone can take today to drastically improve their sleep. Even if you've struggled with sleep for your whole life, it's never too late to address this key aspect of your health.

Here are a few general tips: 

  • Aim for 8-9 hours of sleep each night. How much you need depends on a variety of factors, such as age, activity level, and genetics, but any less 7 hours per night seems to be associated with negative health outcomes. 
  • Maintain a consistent sleep schedule. This entrains the nervous system to orchestrate sleep-related hormone release more efficiently. 
  • Maximize light exposure first thing in the morning, and as much as possible during the day. Early light exposure sets a countdown for the release of a hormone called melatonin at night, which is required to initiate sleep. 
  • Keep the room at a relatively cool temperature. Your body needs to drop a couple of degrees to get to sleep.
  • Avoid screens for at least an hour before bed. Blue light signals to your brain that it’s still day-time, and inhibits melatonin release. If you use your phone as an alarm, and struggle to stay off social media when it's at arms length, here's a life-hack: buy an old-school alarm clock and keep your phone out of the bedroom entirely. 
  • Steer clear of caffeine intake after 10 a.m. Caffeine inhibits the buildup of a key molecule that makes us drowsy, called adenosine. 

Read about these strategies in more detail, here. 

Note: while most of us can improve our sleep significantly by optimizing the most basic aspects of sleep hygiene, if your struggles stem from a medical condition such as insomnia, sleep apnea, or anxiety, please consult a professional. 


If you feel like you need an extra push to get your sleep quality to where it needs to be, consider trying Dr. Schmidt’s Restful Sleep Formula, an expertly formulated natural supplement containing six science-supported, herbal ingredients. To learn more about the science behind Dr. Schmidt’s formulation, check out this article. 

Bottom Line 

By making sleep a priority, you can support your immunity and protect yourself against illness and disease. It's time to unlock the power of sleep and harness its benefits for a healthier, happier you. Turn off the screens, take a deep breath, and let your immune system recharge as you catch some much-needed Zs. 


Video: Sleep scientist Dr. Matthew Walker discusses the relationship between sleep and immunity. 


[1] Cohen, S., Doyle, W. J., Alper, C. M., Janicki-Deverts, D., & Turner, R. B. (2009). Sleep habits and susceptibility to the common cold. Archives of internal medicine, 169(1), 62-67.  

[2] Patel SR, Malhotra A, Gao X, Hu FB, Neuman MI, Fawzi WW. A Prospective Study of Sleep Duration and Pneumonia Risk in Women. Sleep. 2012;35(1):97-101. 

[3] Opp MR. Sleeping to fuel the immune system: mammalian sleep and resistance to parasites. BMC Evol Biol. 2009;9:8. 

[4] Irwin, M., McClintick, J., Costlow, C., Fortner, M., White, J., & Gillin, J. C. (1996). Partial night sleep deprivation reduces natural killer and celhdar immune responses in humans. The FASEB journal, 10(5), 643-653. 

[6] Baldwin, D. C., Daugherty, S. R., Tsai, R., & Scotti, M. J. (2010). A national survey of residents' self-reported work hours: thinking beyond specialty. Academic Medicine, 85(12), 1811-1816. doi: 10.1097/ACM.0b013e3181fa3481. 

About our editorial team

The TWC Editorial team is comprised of various wellness practitioners from physiotherapists, acupuncturists, fitness instructors, herbalists, and MDs.

This article does not constitute medical advice. Please consult a healthcare provider for proper diagnosis and treatment.
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