Understanding how sleep affects the immune system
Poor sleep is bad news for your physical, emotional, and mental wellbeing. For example, it can increase the risk of developing serious diseases, and worsen existing conditions such as depression, chronic pain, and anxiety. Consistently bad sleep habits can leave you feeling low, unproductive, and can even affect your decision-making skills. And, of course, understanding how sleep affects the immune system is more important than ever during the current pandemic.
How sleep and overall health are linked
Your body needs sleep to repair and heal after the general wear and tear of the day. One important step in this process is the release of hormones such as growth hormone which helps to repair tissue and aids in wound healing. As you sleep, the brain gets to work processing, consolidating, and storing useful information, and getting rid of unwanted information. The brain adjusts itself to ensure optimum memory, learning, problem-solving, concentration, and decision making.
Poor-quality sleep (and a general lack of sleep) not only hinders your decision-making skills, but also increase the risk of diabetes, obesity, heart disease, and metabolic disease.
However, it is the connection between sleep and the immune system that we are exploring here.
You may be familiar with the old notion, “sleep is the best medicine”, which is a fair statement in many ways.
Sleep allows the body time to heal and recover after illness, infection, and injury (both physical and emotional). These are not mere assumptions; they are soundly backed by science. Research shows that poor sleep increases the risk of getting sick and may even reduce the protective effects of vaccinations. Interestingly, recent research shows that sufficient, quality sleep can improve the way T cells destroy pathogens and infected cells. We have referenced many of these research papers at the end of this article.
The question remains, how does sleep affect the immune system? Kel Stuart, founder of SANUSq, suppliers of high-quality liposomal supplements and herbal products, provides the answers in this well-researched article:
Sleep and immunity
As you sleep, your immune system releases cytokines, special proteins that are released when the body is stressed, infected, inflamed, or experiencing trauma. When you do not get enough quality sleep, your body will not produce and release sufficient cytokines to control infection and disease.
It makes sense, therefore, that research shows that people who don’t get enough sleep are more susceptible to infection (especially upper respiratory varieties). Your sleep quality and quantity are also a big factor in how well (and how fast) your body recovers after falling ill. In short, sleep influences your risk of contracting an infection, and how well the body responds to that infection. Later, we will discuss the fascinating way sleep may also determine the efficacy of vaccines.
An insightful study on sleep and immune systems
A 2017 study discovered that chronic sleep deprivation can lead to suppressed immunity, pressing the fact that sleep is crucial for a strong defence system.
Researchers used short-term sleep deprivation (under controlled laboratory conditions) to gauge how poor sleep affects immunity. They found that sleep deprivation can increase the activation of immune cells and inflammatory proteins. This study showed that short-term sleep deprivation negatively affects the immune response carried out by circulating white blood cells. 
According to the lead researcher and author Dr. Nathaniel Watson:
“The results are consistent with studies that show when sleep deprived people are given a vaccine, there is a lower antibody response and if you expose sleep deprived people to a rhinovirus they are more likely to get the virus.”
“This study provides further evidence the significant relationship between sleep and overall health and well-being, and particularly to immune health.” 
Studies show that poor sleep increases your chances of catching the common cold.  In the aforementioned study, people who got fewer than 7 hours of sleep were at increased risk of catching a cold after being exposed to the virus. Those who got 8 or more hours of sleep were in a far safer position. 
The relationship between sleep and the immune system is a two-way street. You need sufficient and quality sleep to build a strong immune system that fights against infections. However, sleep is negatively affected when an infection triggers the immune system.
“Lack of sleep weakens your immunity and makes you vulnerable to getting an infection. Sleep strengthens immune response and helps release cytokines and antibodies that fight infection and inflammation.”
Sleep improves T-cell function
Sleep is the best tool when fighting infections and healing from their effects. A paper published in 2019 showed that sleep improves the function of an immune cell called a “T cell”. This smart cell’s job is to identify and destroy cells that have been infected by a virus.  T cells are constantly circulating in the bloodstream, on the lookout for virus-infected cells. When they identify one, they activate a sticky protein called “integrin” that allows them to stick to the cell and destroy it.
Interestingly, scientists found that stress-related hormones such as adrenaline and non-adrenaline, prostaglandins (triggered by inflammation and pain), and adenosine hinder the T-cell’s ability to activate integrins. This means that T cells are unable to properly attach to their target cells. This correlation was previously unknown and is an important piece of information in the study of the sleep-versus-immunity relationship.
How are sleep and T-cell response related?
The previously mentioned study showed that sleep improves the ability of T-cells to stick to infected cells. To test this finding, the research team extracted T-cells from healthy subjects, either while they were asleep or awake for a whole night.
They discovered that T-cells from the volunteers who slept all night showed lower levels of stress hormone and higher levels of integrins than those from the subjects who stayed awake. This occurred because stress hormones and prostaglandins decrease during sleep, allowing adhesion molecules (integrins) to be activated and released.
On the flip side, poor and insufficient sleep boosts the levels of molecules that make T-cells less sticky, hindering their ability to fight infections. The research team produced evidence to show that even mild sleep deprivation (as little as two hours under the recommended duration) can reduce the stickiness of T-cells.
The researchers discussed that their findings apply to conditions like depression, chronic stress, shift work, and ageing where impaired sleep is a common factor.
“Sleep can improve the function of T cells, immune cells that recognize and kill virus-infected cells. It is because production of various molecules, like stress hormones and prostaglandins, is less during sleep. These molecules reduce the efficiency of T cells to latch onto and kill the target cells.”
Poor sleep can reduce the efficacy of vaccinations
We have discovered that lack of sleep hinders your immune function and leaves you wide open to infection. However, poor sleep can also reduce the effectiveness of vaccines, shown by a reduced production of antibodies in adults and infants. 
A fascinating study found that people who slept for fewer than six hours per night displayed lower antibody responses to a hepatitis B vaccine than those who slept for more than six hours.  This correlation was expected by the researchers. However, they did not expect to find that the reduced levels of antibodies continued, even after six months.
Studies like this show how proper sleep affects the immune system and boosts the production of antibodies. Plus, poor sleep fluctuates hormones such as cortisol (the stress hormone) and growth hormone, both of which are important in proper immune function.
“Poor sleep reduces your immune response to vaccines, whereas good sleep helps in the production of infection-fighting antibodies.”
Are naps an effective way to counteract poor sleep and boost immunity?
According to the Sleep Foundation, taking two short naps can alleviate stress, and reduce the negative effects of poor sleep on your immune system.
While this is great news, it’s important to understand that naps must be taken at the right time or they can hinder your ability to sleep properly at night.
Naps that are too long can leave you feeling disoriented and sluggish. Alarmingly, research has suggested that naps that exceed one hour can negatively affect your heart health and longevity, especially for people who get more than 6 hours of sleep per night. 
The same study suggests that the ideal nap duration is 30 minutes or less, as it may support and improve heart function, especially for those who struggle to get sufficient sleep at night.
Your age and overall health will determine how naps can benefit you. For example, pregnant women, the elderly, infants, and those sick or recovering from surgery can greatly benefit from napping. However, if you are young and healthy, the benefits of day-time naps are few.
Tips for improving your sleep
The odd sleepless night here and there is very normal. However, when you constantly struggle to fall asleep and stay asleep, this is a serious issue that can lead to serious insomnia.
Sleep trouble and insomnia can be caused or exacerbated by stress, medical issues, chronic pain, depression, and shift work.
Another trigger many of us are guilty of is using tech devices in bed, such as cellphones and laptops.
Health conditions can also be the cause of health struggles and insomnia. Conditions such as depression, anxiety, thyroid disorders, chronic pain, heartburn, diabetes, fibromyalgia, and muscle spasms can aggravate sleep trouble. The catch is that poor sleep can worsen these health conditions, further deepening the tricky cycle.
If you are struggling with poor sleep, it’s important to see your doctor so they can investigate possible underlying conditions.
Quick tips for maintaining a healthy sleep routine
- Stick to a consistent sleep and wakeup routine
- Create a pre-bed routine that induces sleepiness and relaxation. Baths, reading, music, or meditation are all helpful
- Wait until you feel sleepy before going to bed
- Stick to water and decaffeinated tea before bed, and avoid coffee, alcohol, sugar, and energy drinks
- Avoid napping in the afternoon, especially after dinner
- Ensure your bedroom is quiet, cool, and dark
- Manage work and life-related stress
- Make sure you get some healthy sun exposure during the day
- Eat a healthy diet, get enough exercise, and avoid sitting for too long at once
- Avoid using your phone in bed, and put the screens away in the lead-up to bedtime
Can supplements help with sleep?
Many supplements can help to improve sleep quality and duration and aid in establishing a regular sleep routine. One of the most common supplements is magnesium, known for calming the nervous system, reducing stress, and inducing a sense of sleepiness.   Magnesium can also help in the relief of conditions like chronic pain, anxiety, depression, and migraines, all of which can hinder sleep quality.
To boost immunity and improve sleep quality, you should approach your health holistically by incorporating a healthy diet, exercise, and lifestyle choices.
Clearly, getting consistent healthy sleep is more important than we may previously have thought. Considering that the world is dealing with the COVID-19 pandemic, proper sleep is more important than ever, especially when it is so clear how sleep affects the immune system.
- SA Gharib, MD et al. Transcriptional Signatures of Sleep Duration Discordance in Monozygotic Twins. Sleep, January 2017. Sleep.
- “Chronic sleep deprivation suppresses immune system: Study one of first conducted outside of sleep lab.” ScienceDaily. 2017
- Prather et al. Behaviorally Assessed Sleep and Susceptibility to the Common Cold. 2015. Sleep.
- Cohen et al. Sleep habits and susceptibility to the common cold. Arch Intern Med. 2009.
- Dimitrov et al. Gαs-coupled receptor signaling and sleep regulate integrin activation of human antigen-specific T cells. Journal of Experimental Medicine. 2019.
- Franck et al. Infant Sleep After Immunization: Randomized Controlled Trial of Prophylactic Acetaminophen. Pediatrics. 2011
- Prather et al. Sleep and antibody response to hepatitis B vaccination. Sleep. 2012.
- Long naps may be bad for health. European Society of Cardiology. 2020.
- Abbasi et al. The effect of magnesium supplementation on primary insomnia in elderly: A double-blind placebo-controlled clinical trial. J Res Med Sci. 2012
- Cao et al. Magnesium Intake and Sleep Disorder Symptoms: Findings from the Jiangsu Nutrition Study of Chinese Adults at Five-Year Follow-Up. Nutrients. 2018