For a great many Americans—some estimates put the figure as high as 70 million—getting a good night's sleep is just a dream, alas. The reality, according to survey after survey, is that the number of hours we spend sleeping has been shrinking in recent years. In fact, according to the Centers for Disease Control and Prevention, this collective dearth of sleep is currently at epidemic proportions.
Moreover, we all have our own ways of coming up short on shut-eye. Some of us have erratic, unpredictable sleep; we might lose most or all of a night for various reasons. Others are more consistent but not in good ways; we seem to habitually experience shortened or poor-quality sleep. Toss in shift work, chronic health issues—physical as well as mental— recurring stress, even relentless nightmares, and you have the makings of a nation that can seem to be running on sleep fumes.
In addition to the obvious wear and tear of too little sleep—bad moods, fatigue, poor performance at school or work—we also have the burden of being reminded by countless articles, books, and sleep experts that restful, rejuvenating sleep is an absolutely essential, nonnegotiable element for good health. No pressure, right?
Well, the experts are right. But by more fully understanding why they are right, we can better face our sleep problems with potential remedies. One of the keys in this understanding is to appreciate the interconnection between sleep and our immune systems.
Most of us now know that sleep is not a passive state and there are different types of sleeping states in which both the body and the brain are active. It's a good thing to remember if we find ourselves lamenting the fact that we spend so many of our hours seemingly dead to the world; by age 70, the average person has spent a cumulative total of between 20 and 25 years asleep. In fact, the physiological "work" done during sleep may be why our need for sleep survived mammalian evolution, despite the potentially vulnerable state in which it places us. Some of the most important work that is done while we're asleep involves the immune system.
The link between sleep and immune function is complicated. As sleep expert Michael Breus, PhD, notes, "In talking to my patients, I realize that while most of them understand that excessive inflammation can be harmful ... they don't know that poor sleep is a contributor to inflammation." It is a two-way street, explains Breus. "The relationship between inflammation and sleep brings together two complex and fundamental body systems." Not only are sleep and the immune system dependent on each other for optimal health, but it's a feedback system in which problems in one system can be either a cause or an effect of problems in the other.
There are chemical markers that reflect the interaction between sleep and inflammation—such as C-reactive protein, or CRP, a molecule produced in the liver in response to inflammation signals. Poor sleep, in either quantity or quality, is often associated with an increase in CRP levels. It is also known that inflammation can be linked to a number of diseases, such as type 2 diabetes and heart disease (some research suggests that chronic sleep deprivation may double a person's risk of dying of heart disease). Many experts are particularly worried by the public health ramifications posed by the relationship between poor sleep, inflammation, and obesity.
Getty Images / Moyo Studio
The link between poor sleep and obesity is also an example of feedback loops that can make the problem worse. According to the Harvard Health publication Fighting Inflammation, "With insufficient sleep, you produce higher levels of hunger hormones and lower levels of satiety hormones, causing you to overeat—in particular, you're likely to crave refined carbohydrates. It is also possible that fatigue may cause you to be less physically active, and thus miss out on exercise's weight-loss and anti-inflammatory benefits."
Poor sleep can also be part of the feedback loop in depression, according to Fighting Inflammation: "Depression shares many of the same characteristics, risk factors, and symptoms as immune-based inflammatory responses. We know that low mood, appetite loss, sleep disturbances, trouble concentrating, and a lack of energy are clear hallmarks of depression, but these are also signs of inflammation." Links between sleep disturbances and immune response have also been investigated in schizophrenia and alcohol dependence.
These relationships are made more complex by the fact that "sleep cycles, duration, and quality change significantly over a lifetime," wrote Norah Simpson and David Dinges more than a decade ago in "Sleep and Inflammation" in Nutrition Reviews. And as we age, it isn't just that we wake up at night more often and take more naps; there are "changes in numerous other domains of sleep," including "sleep architecture, circadian rhythms, and sleep pathologies," they say.
Moreover, says Breus, "the differences in the ways women and men respond to sleep loss are important and understudied. Sleep's effects over inflammation may be one area where women and men experience different degrees of consequence— and that could have implications for their vulnerabilities to chronic disease."
Sleep is important not only for fighting off microbial infections. It also plays a role in maintaining a healthy microbiome, explains Breus. "How does a gut become unhealthy? Poor diet, stress, medication, and illness are all contributors. So too are disrupted circadian rhythms and poor sleep. Poor and insufficient sleep appear to change the composition of our natural microbiota, decreasing beneficial bacteria and increasing bacteria associated with disease."
As Breus emphasizes, the challenge is that inflammation often has no obvious symptoms. And while the sheer complexity of the sleep-immune interconnection may seem like the bad news, on the other hand, that may be the good news too. The complexity of the interconnection offers an enormous number of avenues and opportunities that we can take to contribute to our well-being.
Getting better sleep is a battle you can wage on several fronts. First, some general principles. Is your schedule overbooked? It happens to us all, but let your new motto be, When the going gets tough, don't tough it out. Instead, protect yourself (and your sleep) by sticking to a healthy sleep routine and reminding yourself that any short-term benefits from cutting back on sleep are, first, most likely illusory, and second, bound to backfire, usually sooner than later, though we tend not to notice it until too late. Real productivity thrives on sleep. And when you are feeling stretched thin, take advantage of as many coping strategies as you can, which might include naps or regular meditation to reduce stress.
There is also an ever-expanding range of technological innovations that can come to your aid. The past few years have seen an explosion in AI-powered apps that can gather and track a full spectrum of sleep data, down to the minute. There are smart alarm clocks that can simulate the light of a natural sunrise every morning; smart beds and even pillows that are loaded with sensors, pumps, and vibrating panels designed to detect snoring and adjust accordingly; as well as sophisticated earbuds and white-noise machines that aim to soothe and headphones that aim to shut out all noise. All of which can help you be smart in knowing that a good night's sleep is also serving your immune system