How Sleep Affects Your Immunity (SQ-131)
Inadequate sleep can take a huge toll on your health. Lack of sleep can increase your risk of certain diseases and aggravate conditions like depression, anxiety and chronic pain. It can affect your mood, productivity and decision making, wreaking havoc on various aspects of your physical, mental and emotional well-being.
Sleep and health
During sleep is when your body gets into healing and repair mode. During sleep, your body releases a number of hormones, such as growth hormone, that repair the body from everyday wear and tear. These hormones help in tissue repair and regrowth and facilitate wound healing.
During sleep, your brain stores, processes and consolidates information. It even removes unwanted information and gets rid of toxic by-products. Your brain re-arranges itself in a way that helps memory, learning, concentration, decision making and problem solving.
All these restorative tasks help rejuvenate your body and mind to face yet another day of mental, physical and emotional challenges.
Insufficient sleep clearly interferes with your ability to give your best, make sound decisions, be alert and learn better. Long-term lack of sleep also increases your risk of diabetes, metabolic syndrome, obesity, and heart disease.
Can sleep affect immunity? Well, going by conventional wisdom, sleep is the best medicine. Sleep helps you heal and recover from infections, injuries and disease. Interestingly, this has a scientific basis. Research indicate that poor sleep increases one’s risk of falling ill and even reduces the protection offered by vaccinations. In fact, latest findings indicate that sleep improves the efficiency of T cells in destroying pathogens and infected cells.
Let’s find out how sleep affects your immunity.
Sleep and immunity
When you are sleeping, your immune system releases cytokines. These are proteins that your body typically releases during infection, inflammation, stress and trauma. Lack of sleep means your body doesn’t produce enough cytokines to keep infections and diseases at bay.
Research indicates that people who don’t get good amounts of sleep are far more vulnerable to infections, especially upper respiratory infections, when they are exposed to a virus. The amount of sleep you get also determines how fast your body springs back after getting sick. In other words, sleep can influence infection outcome. And as we will explore later, it can even determine the efficacy of vaccines, in both adults and infants.
A 2017 research found that chronic sleep deprivation can lead to a suppressed immune system. The study highlighted that getting enough sleep is important for your immune system to work at its best. Short-term sleep deprivation, under laboratory conditions, has been linked with increased activation of immune cells and increased levels of inflammatory proteins in the body. This real-time study, done on twins in a natural environment, showed that chronic short sleep adversely influences the response mounted by the circulating white blood cells. 
According to the lead 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 of sleep to overall health and well-being particularly to immune health.” 
Studies show that sleep deprivation increases the likelihood of catching the common cold.  In this study, people who slept for less than 7 hours were more likely to develop a cold after being exposed to the virus than people who got 8 hours or more of sleep. 
Sleep and the immunity share a two-way relationship. You need adequate sleep for building healthy immunity. And sleep quality affects how your immune system responds to the microbial threats and infections. On the other hand, your sleep pattern is disrupted when an infection activates your 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 function of T cells
When it comes to healing and fighting infections, sleeping is the best medicine. A 2019 research paper found that sleep improves the function of T cells, a type of immune cell that specializes in identifying and killing cells that have been infected by a virus. 
These immune cells are constantly patrolling in the bloodstream, looking for infected cells. When T cells have identified a virus-infected cell, they activate integrins – sticky proteins that allow T cells to stick to and destroy infected cells. In other words, activation of integrins is an important mechanism through which T cells kill pathogens.
Researchers found that hormones such as adrenaline and non-adrenaline, prostaglandins (hormones released during pain and inflammation), and adenosine block T cells to activate integrins. This reduces the ability of T cells to actively attach to their target cells.
While it was already known that these molecules can reduce immune functions, their role in decreasing the efficiency of T cells to latch onto their target cells was not known.
How is sleep related to the T cell response? This study further found that sleep can improve the ability of T cells to stick to the infected cells. In order to test this, the team took T cells from healthy volunteers, while they either slept or stayed awake all night.
They found that T cells from people who slept had lower levels of stress hormones and higher activation of integrins than the cells extracted from people who remained awake through the night. This happened because the levels of stress hormones and prostaglandins naturally decrease during sleep, leading to the activation of adhesion molecules.
On the other hand, getting too little sleep increases the levels of molecules that make T cells less sticky, hence less proficient in fighting infections. The researchers were able to show that even a couple of hours of sleep deprivation can compromise the stickiness of T-cells.
The researchers stated that their findings are also relevant for conditions such as depression, chronic stress, aging, and shift work, where impaired sleep is an important parameter.
“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 also reduce the efficacy of vaccinations
Skimping on sleep not only compromises your immune function and leaves you susceptible to infection, it can also reduce the effectiveness of vaccines.
Sleep deprivation before or after vaccination is related to reduced production of antibodies for both adults and infants. 
A study found that people who got less than six hours of sleep per night showed lesser antibody response to a hepatitis B vaccine than people who slept more.  Skipping a good night’s sleep impacted the efficiency of the vaccine. While the researchers expected to see the link between immune response and sleep duration, what stood out was continually reduced levels of antibodies - even after six months!
The study showed that good sleep regulates the immune system and helps in the production of antibodies. Sleep deprivation unsettles cells that help in antibody production. It also fluctuates hormones like cortisol and growth hormone, that are intricately linked to the working of your immune system.
“Poor sleep reduces your immune response to vaccines, whereas good sleep helps in the production of infection-fighting antibodies.”
Do naps help?
Napping has been long used as a powerful technique to reduce day-time fatigue, boost performance and improve mood and even alertness. According to the Sleep Foundation, taking two short naps can reduce stress and counter the negative effect of poor sleep on immunity.
However, it is important to note that napping at the wrong time can backfire and negate all your efforts to sleep properly at night. Long naps can make you feel groggy and disoriented. In fact, latest research suggests that napping for more than an hour can be detrimental for heart health and longevity, especially for those who sleep for more than 6 hours at night. 
However, short naps of around 30 minutes or less pose no danger to heart health. In fact, napping for short durations might even improve cardiovascular health in people who don’t sleep too well at night, according to the same research.
The benefits of napping should be considered in context of individual age and health. For example, infants, pregnant women, elderly and those sick or recovering from a surgery are good candidates for napping. However, for otherwise young and healthy adults, there are no substantial benefits for taking a mid-day snooze.
What can you do to improve your sleep?
It is normal to experience a sleepless night or two due to a temporary situation. However, it is serious when falling asleep becomes a daily struggle. Some people may have a hard time dozing off or staying asleep on a regular basis. This can lead to mild or even fully blown insomnia.
Factors such as stress, an underlying medical issue, depression, chronic pain, working in shifts, and sleep disorders can trigger or worsen insomnia. Another trigger known to disrupt a healthy sleeping pattern is using a ‘phone in bed.
Here is a quick guide to maintain a healthy sleep regime
- Maintain a regular sleep and wakeup schedule.
- Make a pre-sleep routine to help you relax; take a bath, read a book, listen to music or practice meditation
- Don’t go to bed if you are not feeling sleepy
- Cut down on caffeine, alcohol, sugar and energy-based drinks before bedtime
- Avoid napping, especially in the evening or after dinner
- Keep your room dark, quiet and cool
- Find ways to reduce stress
- Exercise regularly and eat healthy
- Stop using a ‘phone in bed and cut down on screen time before going to bed
- Go out in the sun during the day
Some health conditions like muscle spasms, fibromyalgia, chronic pain, diabetes, heartburn, thyroid disorders, anxiety and depression could be the reason you are having such a hard time falling or staying asleep at night. While these conditions aggravate poor sleep and insomnia, inadequate sleep further worsens these health issues and even increases your sensitivity to pain. It is important to see a doctor to manage underlying conditions that are causing your sleep problems.
Can supplements help with sleep?
Certain supplements can help improve sleep quality. For example, magnesium calms the nervous system, which helps you sleep and improve symptoms of insomnia  . Magnesium also helps in conditions such as migraine, anxiety, depression and chronic pain. It also reduces stress. Since poor sleep could be a direct or indirect result of stress, anxiety and pain, managing all these conditions can be especially useful in promoting healthy, restorative sleep that you need every day.
Herbs like ashwagandha, Jiaogulan, reishi and chamomile are also widely used to improve sleep quality. To know more about herbs that help in stress and anxiety, you can read more here.
Taking holistic steps, through diet, exercise and a healthy lifestyle, to not only improve your sleep but also boost your immunity.
It seems that getting good sleep is far more important to our health than we think.
And when the entire world is grappling with the current COVID-19 pandemic, this fact needs to be reiterated more than ever. It is important to keep your immune system strong, and maintaining healthy sleeping pattern is one of the ways to achieve strong immunity.
- 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