Sleep is as crucial as food for keeping us alive and healthy, yet worldwide the typical adult does not get enough sleep. Sometimes it’s the simple things that keep us from a good night’s sleep, like an overactive brain or a neighbor’s barking dogs.
More complex problems that can disrupt sleep include chronic insomnia, snoring, and sleep apnea. This article will help you solve some of the simple problems that get in the way of a restful night’s sleep and explain why sleep is so important – particularly for the immune system.
Over 166,000 studies on sleep exist on the PubMed website, run by the National Institutes of Health. This plethora of sleep research convincingly demonstrates that lack of sleep and sleep disorders affect more people across the world than previously thought.
These conditions adversely impact health by increasing risk of disease, contributing to inflammatory conditions, creating lost time from work, increasing incidence of accidents due to lack of attention, and many other problems. One study stated that sleeping disorders even contributed to mortality !
According to the American Sleep Association, 50-70 million American adults have a sleeping disorder . A 2011 study found that 20% of French adults aged 25-45 slept 90 minutes less than they actually needed for optimal health .
The Importance of Sleep
While we sleep, our bodies take time to rest up from the day’s activities and repair themselves.
When a person does not sleep well, the effects can immediately be felt by a decline in overall well-being, performance, and cognitive function, as well as feeling sleepy or fatigued the next day.
Long term sleep loss can result in more serious health problems including increased risk for:
- cardiovascular disease
- inflammatory conditions
- impaired glucose tolerance
- disrupted hormonal function
- and even premature death
Have you ever thought about what’s going on in your body while you sleep? Here are just a few of the things that occur when you snooze:
- The brain is busy clearing away toxic by-products, processing information received during the day, and dumping unneeded information
- Heart rate, blood pressure, and breathing slow, body temperature drops, and digestion slows
- The muscles relax and blood supply increases
- Two systems of the body involved with stress, the hypothalamus–pituitary–adrenal axis (HPA axis) and the sympathetic nervous system (SNS), are down-regulated, and blood levels of stress related hormones, like cortisol and adrenaline, drop
- The liver moves from detoxification processes to renewing and rebuilding
- Dozens of hormones, proteins, and chemicals are delivered to target organs to build all of the different types of cells the body needs
- The immune system gets a recharge
The Impact of Sleep on Your Immune System
There is a delicate interplay between the immune system and sleep. The sleep we end up getting directly impacts how well the immune system functions.
First, a quick discussion on how the immune system works: the immune system is a collection of cells, tissues, and other molecules that works to protect the body from hundreds of different microbes and toxins.
The Immune System is Divided into Two General Types
#1: Innate Immunity – consisting of cells and proteins that are always present and which work quickly to mobilize and fight microbes as they are encountered, such as when bacteria enters a cut or abrasion in the skin.
#2: Adaptive Immunity – further divided into two types of immune responses:
(a) humoral immunity, mediated by antibodies created by B lymphocytes
(b) cell-mediated immunity, mediated by T lymphocytes.
Adaptive immunity is required to act against pathogens that can invade or overcome innate immune cells. This process takes a little longer than innate immunity, but once activated, adaptive immune cells work hard to neutralize or eliminate the invasion.
This branch of the immune system has memory cells that remember the aggressor and act specifically against it. This explains why there are some illnesses one can only get once in a lifetime, because afterwards these immune memory cells immediately recognize that threat and neutralize it, causing the body to become “immune” to that pathogen.
Studies have shown that even short-term loss of sleep can have a significant impact on how well the immune system functions. What appears to happen during periods of sleep loss is that the immune system triggers an increase in inflammatory markers.
Even a relatively modest restriction of sleep from eight hours to six hours per night for eight nights straight can effectively increase the level of pro-inflammatory cytokines (cell signalers) in the body, thus increasing inflammation .
Sleep also plays a major role in both adaptive and innate immune responses.
During nocturnal sleep, T cells increase production of interleukin-2 (IL-2), interleukin-12 (IL-12), and interferon-gamma (IFN-gamma). These are all cytokines involved in the adaptive immune response.
Nocturnal sleep also promotes an increase in natural killer (NK) cell activity, part of innate immunity, and induces the release of prolactin and growth hormone (GH) during the early part of the night .
NK cells roam the body looking for tumor cells, viruses, and other microbes. Prolactin and GH work to enhance the proliferation and differentiation of T cells and promote the activity of certain cytokines within the immune system.
It is easy to see, then, how even just one night of lost sleep can adversely impact the immune system. Fortunately, our bodies can bounce back from this “insult” relatively quickly unless sleep deprivation becomes chronic. This is important as long-term sleep deprivation can have catastrophic results for health.
The Psychoneuroimmunology Perspective
The field of psychoneuroimmunology (PNI) is the study of the interplay between psychological processes, the nervous system, and the immune system. And it has some valuable insights regarding sleep and immunity.
The real value of PNI in sleep dysfunction is that it seeks to understand how sleep, stressful events, and negative emotions influence the immune system.
PNI researchers have discovered that pro-inflammatory cytokines contribute to both fatigue and sleep disturbances. One of the questions that PNI researchers have struggled with is what comes first?
The sleep disturbance which causes a general decline in immune health and triggers the release of pro-inflammatory cytokines, or other pro-inflammatory factors that impact the immune system which create the sleep disturbance.
These are interesting questions, but unfortunately PNI research has few answers for us. A 2015 clinical trial involving 123 older adults with insomnia had some interesting results, however…
Researchers found that Cognitive Behavioral Therapy (CBT) reduced levels of pro-inflammatory cytokines and gene expression. CBT involved multiple components of behavioral intervention by providing sleep education, strengthening associations between bed and sleep, and specific therapy for anxiety-provoking beliefs about sleep.
Also introduced in the trial was the discipline of tai chi, which reduced inflammatory responses. Researchers stated that the combination of CBT and tai chi reduced expression of genes encoding pro-inflammatory mediators .
In a comprehensive review of research, PNI scientists stated that stress-response pathways are often activated in those who experience insomnia, and that relaxation-based approaches such as tai chi, yoga, and mindfulness meditation help to calm these pathways, as well as having a beneficial effect on both adaptive and innate immune responses .
If you don’t currently have a meditative or relaxation practice, this is yet another compelling reason to implement one. In another article we explore 10 reasons why you may not be getting enough sleep and solutions to help you get more quality shut-eye.
If you’re having trouble sleeping, be sure to check out this article on the 5 best essential oils for sleep.