Does Sleep Reduce Inflammation?

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We all know how important a good night of sleep is in terms of how we feel mentally. But new research suggests that catching the right amount of Z’s is equally important to how our bodies perform physically.

Specifically, scientists now believe there is a strong connection between a person’s average amount of sleep and their level of chronic inflammation.

In this article, we’ll take a closer look at how sleep and inflammation are connected, how not getting enough sleep can increase chronic inflammation, and if it is possible to reduce inflammation by getting better sleep (and how to do that!).

What Is Inflammation?

Inflammation is the natural process of swelling that occurs when your body’s immune system targets a pathogen or reacts to an injury.

White blood cells and the substances they produce create inflammation in order to restrict the movements of potentially harmful bacteria, viruses, and toxins. Without the inflammatory process, these pathogens would be free to move from the site of the injury or infection and spread throughout your body.

Inflammation is a necessary and natural reaction.

However, it is possible for inflammation to occur when no pathogen is present or for your immune system to react too aggressively to a situation. This typically happens when the immune system mistakes the body’s own cells for a foreign invader and starts attacking them.

In extreme cases, this inflammation results in autoimmune disease, such as type 1 diabetes, lupus, and rheumatoid arthritis.

But even in those who don’t have an autoimmune disease, chronic inflammation can lead to problems with how the body operates. The longer this inflammation occurs, the more side effects the person is likely to experience.

According to Ansley Hill, a Registered Dietician and Nutritionist, sleep habits can play a significant role in a person’s inflammation levels.

“An often-overlooked element to managing inflammation,” she says, “is adequate sleep. Poor sleep hygiene can contribute to a variety of metabolic disruptions that favor an increased inflammatory response. Moreover, recent research suggests an association between inadequate or irregular sleep patterns and increases in inflammatory biomarkers, especially for women.” 

How Are Sleep and Inflammation Connected?

How sleep can affect a person’s level of inflammation has to do with the fact that sleep and the immune system are connected both through our sleep-wake cycles and through direct communication.

Our circadian rhythm—or internal clock—dictates when we feel sleepy and when we wake. It also determines when our immune system is the most active and when it spends the most time repairing itself.

If our sleep-wake cycle becomes disrupted due to poor sleep habits, then the immune system’s cycle of repair and action also becomes disrupted.

Studies have also shown that there are strong “reciprocal connections” between the central nervous system, the immune system, and sleep. Proper sleep enhances a person’s immune defenses. But the immune system can also promote and disrupt sleep through different signaling pathways.

When a person experiences an infection, the immune system produces chemical signals that promote sleep to aid in recuperation. When the body experiences stress, the immune system will signal the body to stay awake and alert. This is believed to be a holdover from when our ancestors had to deal with the threat of predation.

When sleep is disrupted by external forces (mental stress, poor habits, etc.), this feedback loop is negatively affected.

How Sleep Loss Leads to Inflammation

It is the disruption of the immune system-sleep feedback loop that contributes to excess inflammation in the body.

How exactly, though, sleep loss leads to inflammation is still being studied. The three most likely causes have to do with improper immune activation, elevated blood pressure, and increased insulin resistance–all known side effects of poor sleep habits.

Immune Activation

As discussed in the scientific paper, Sleep Loss and Inflammation, multiple studies have found that both acute and chronic sleep loss contributes to increased white blood cell count.

In fact, even one night of restricted sleep can cause measurable differences in white blood cell activity and in the amounts of pro-inflammatory chemicals released by these cells into the bloodstream.

This triggered immune activation in response to restricted sleep could be due to a reversed feedback system. In other words, we know natural immune activation can disrupt normal sleep patterns. It is also possible that this system can be reversed so that disrupted sleep patterns trigger immune activation by utilizing those same pathways.

Additionally, there is a known connection between stress, sleep, and immune activation.

Stress is the number one reason people lose sleep. And cortisol, the stress hormone, also causes immune activation. It is possible that poor sleep and inflammation are both simply side effects of stress.

Studies into cortisol levels and sleep deprivation have yet to find that sleep disruption leads to a consistent rise in cortisol. However, some studies have pinpointed a clear cortisol spike in the afternoon and early in the night following poor sleep. This could be enough to increase white blood cell count, especially over time.

Elevated Average Blood Pressure

It is well established that increased blood pressure results in elevated inflammation levels throughout the body and especially in the vascular system. Since blood pressure is lowest during sleep, a decrease in sleep hours results in a person’s average blood pressure increasing.

One theory into the connection between sleep and inflammation says this fact alone could explain why those who sleep fewer than eight hours per night show more inflammation markers.

Even in people with healthy blood pressure, the lack of a significant period of lowered blood pressure overnight could be enough to increase overall inflammation levels.

This process is likely to be even more exaggerated in people who already suffer from high blood pressure. In addition to an increase in inflammation facilitated by high blood pressure during the day, they also experience increased inflammation due to an average blood pressure increase caused by poor sleep.

Insulin Resistance

Sleep loss also affects how well our bodies process glucose.

Multiple studies into metabolism and sleep have found that acute sleep deprivation results in slowed glucose metabolism. This has been shown to be due to the effect of reduced insulin sensitivity.

Insulin, the hormone responsible for “opening” cells so that they can uptake sugar from the bloodstream to use for energy, is known to induce stimulation of multiple pro-inflammatory mediators.

As insulin resistance increases and blood sugar builds up in the bloodstream, the body responds by creating more insulin. As insulin levels increase, so too do the inflammatory mediators and chemicals they stimulate.

At this point, there is no direct evidence that insulin resistance caused by disrupted sleep would be enough to cause chronic inflammation.

Most likely, insulin resistance, an increase in average blood pressure, and immune activation all play a role in increasing and sustaining inflammation throughout the body.

What Can You Do To Improve Your Sleep?

It’s clear that disrupted sleep causes inflammation in the body. So it stands to reason that getting adequate, quality sleep can reduce a person’s inflammation levels. Or, at the very least, help them avoid additional, chronic inflammation.

According to Ansley Hill, “Prioritizing quality sleep can be a relatively simple way to manage inflammation and promote improved metabolic health.”

But wanting to get better sleep and actually getting better sleep are two very different things.

Luckily, there are some simple changes you can make to help improve the quality and quantity of your sleep.

Ansley says, “Easy lifestyle adjustments like limiting screen time before bed, maintaining consistency with sleep and wake times, reducing alcohol and caffeine consumption, or implementing an evening relaxation ritual are all effective and inexpensive ways to improve sleep quality.”

If you suffer from chronic inflammation or health conditions like high blood pressure or autoimmune disease, or if you’re just interested in feeling better every day, then improving your sleep habits is one of the best things you can do for yourself.

Sara Seitz