January 12, 2021 10 min read
The simple answer is, yes sleep can make you sick. What’s not so simple is the intricacy between your immune system and your sleep (and all the things that happen while you’re asleep).
Catching Zs comes easy for some and hard for others, but whichever camp you fall into it’s important to do all you can to ensure that you’re taking care to sleep well. Not getting enough sleep can have both short term consequences and long term ones, and “catching up” on sleep when it comes to your immune system isn’t really a thing.
While we do know what happens when we sleep (to some extent), we still don’t know why it happens the way it does and for what reason. While this gives off some mysterious vibes, there’s still a whole lot that we can tell from studying this interesting and fundamental function of the human body.
And since the immune system and sleep share such a close relationship, sleep can affect your immune function just as much as your immune system can affect your sleep.
Staying on top of sleep and health takes a special kind of hygiene—sleep hygiene. To get the most out of hitting the hay, we’ll go over several strategies to maximize your sleep gains. But to understand sleep, let’s first take a look at the immune system.
As the name suggests, the immune system is a complex system.
It consists of many mechanisms and lines of defense in order to keep you from falling ill. The one line of defense most people are familiar with are leukocytes (white blood cells). Their job is to identify pathogens and remove them from our systems.
The identification is aided by the use of cytokines—“messenger” proteins that act as communicative pathways between cells. In this case, the cytokine would be released from one white blood cell to tell others around it to attack something. Other examples include swelling/redness, which is due to the chemical histamine.
All of the moving parts of the immune system require a balance in order for optimal health to be maintained. For example, a fever can trigger various symptoms such as inflammation, or fatigue. Anything from diet, exertion, hydration, and sleep can throw the system off and make it more difficult to both protect your body from pathogens fight off any that have already made their entrance.
One important thing to keep in mind that we’ll cover when we talk about sleep is the two different types of immunities.
Firstly, there’s the innate immunity. This is the protection that refers to all the defense mechanisms that are triggered with the entrance of a pathogen in the body. This ranges from anything from the physical barrier of the skin to chemicals in the blood and white blood cells.
The second type of immunity is adaptive immunity.
Also known as acquired immunity, this is a subsystem of the immune system that consists of specialized cells and processes that are activated once the innate immune response isn’t sufficient to deal with the pathogen. This type of immunity occurs only after exposure to a specific pathogen or vaccine, once your immune cells have “tagged” the attacker.
These two basic categories of immune response both play into how you sleep, and in turn, your sleep also plays into how effective your response is to pathogens. And not only does sleep play a role in immune response, but it’s a very important role at that.
A “good night’s rest” is usually defined as anywhere from 7 to 8 hours, but this is extremely dependant on the person and so each individual should get a good measure of their needs.
This is important because the CDC estimates that 1 in 3 Americans don’t get the amount of sleep they should be getting every night. But why sleep?
Getting the right amount of sleep will improve your attention, memory, and overall behavior. Furthermore, your mental and physical health will also improve. Not only does your mind need time to wind down and de-stress, but your muscles need to recover at some point. If you work out regularly, sleep becomes even more important for your gains. That’s when your muscle fibers heal and grow, so not getting enough sleep means leaving gains on the table.
And due to its ubiquity as a very basic human function, it often goes neglected. Whether that neglect happens due to work or to play, it’s important to try to find the time to give yourself enough of it. It’s often said that you can’t out-train a bad diet, and the same goes for bad sleeping habits. Health requires the trifecta of diet, exercise, and enough sleep—going without one spells bad news.
So, let’s take a look at the specifics surrounding sleep and sickness.
There are several mechanisms through which sleep and the immune system interact—when it comes to both innate and adaptive immunities as well.
A lack of a good sleep schedule has been tied to many short-term and long-term illnesses, and researchers believe that this is due to the fact that poor sleep has extensive consequences on the normal functioning of your immune system.
When it comes to short-term illnesses, the risk of infections in people who don’t get enough sleep is higher. And this doesn’t even take into account dramatic sleep deprivation—heightened risk to infection can be seen in people who get less than 6 to 7 hours of sleep per night. A lack of sleep can make one more susceptible to upper respiratory infections such as the common cold, and the flu.
Even for those who are recovering in intensive care units and have smaller recovery needs, not getting enough sleep has been tied to longer times needed for healing to happen.
Sleep deprivation has been tied to many different long-term health and chronic issues. These include a heightened risk of diabetes, neurodegenerative diseases, cardiovascular diseases, obesity, and chronic pain. In terms of mental health, consistent sleep deprivation has been closely linked to depression in certain individuals.
And while we might feel that we’re able to “catch up” on sleep, even if our sleeping schedule is way out of wack, studies have shown that our immune systems never get used to the new “norm” of poor sleep.
Many of the chemical processes and mechanisms that work to keep our immune system in balance are closely tied to the circadian rhythm. This includes several types of hormones and immune cells (such as T cells) that work to keep your body in tip-top shape. Some of these include prolactin, norepinephrine, and cortisol—neuroendocrine mediators which all exhibit circadian rhythms (the body’s natural, 24-hour clock). T cells also have higher levels of integrin activation when you’re well-rested.
The inflammatory response is a key mechanism of our immune system. Swelling can be extremely helpful for maintaining our health or recovering—at least when it’s only short-term and localized. Chronic inflammation, however, has been suggested to lead to many different types of illnesses.
And when we sleep, certain mechanisms of the immune system “wake up”. One of these is the inflammatory response, driven by cytokines associated with inflammation (i.e. inflammatory cytokines). The production of cytokines that are pro-inflammatory benefits both innate and adaptive immunity, since it allows the body to fight pathogens or repair wounds.
However, even if a person isn’t actively fighting off infectious diseases or healing any wounds, studies have shown that this inflammatory cytokine response still happens. But why?
It’s believed that this nightly inflammatory response helps to build adaptive immune function in the body. Much like sleep helps to consolidate memories and new things we learn, the nightly inflammation can potentially help bolster the memory of your immune system. Much like a vaccine “teaches” our immune cells to fight off certain pathogens, sleeping well consolidates these memories and helps the overall immune response.
But we’re still not sure why this happens during sleep itself. Some researchers postulate that it’s because as our muscle activity and energy expenditure drops, more resources can be put towards the immune system’s tasks. It’s also believed that this inflammation could get in the way of mental and physical activities we do during the day, and so we’ve evolved for inflammation to happen at night.
Furthermore, there’s the production of melatonin that happens a night. This hormone is a way of managing stress levels, and it can potentially mediate the stress arising from sleep inflammation.
But whatever the reason, we do know that sleep is absolutely essential in keeping the delicate balance of our health and immune function. As we begin to wake up each night after (hopefully) 7 to 8 hours of sleep, our bodies slowly ramp down this inflammatory response, as our circadian rhythm comes full circle. This makes it apparent how delicate of a balance everything is—and how essential it is to take care of sleep.
One obvious way that a good sleep schedule can help us is through the aforementioned adaptive immunity.
When we’re vaccinated, a weakened (or deactivated) version of the pathogen is introduced into our bodies. This triggers the immune system and allows it to create a response plan for the specific pathogen. Since our body’s immune system creates these “memories” of pathogens and then consolidates them, it makes sense that any vaccine’s effects would be bolstered through better sleep.
Studies have also backed this up. In one such study, hepatitis and H1N1 vaccines were given to people who didn’t sleep the night after receiving them.
It was found that those who didn’t sleep the night after receiving the vaccine had a measurably weaker immune response. In certain cases, this diminished the effectiveness of the vaccine and could potentially even lead to needing a second dose.
While that study in particular looked at those who didn’t get one night’s sleep the day of the vaccination, other studies have looked at adults who consistently don’t get enough sleep. And, you guessed it, these individuals share reduced vaccine effectiveness. In one study, limiting sleep to 4 hours per night for 6 days and then allowing for 12 hours of sleep for 7 days resulted in halving the antibody production to an influenza vaccine.
Allergic reactions are essentially overreactions of your immune system to things that it shouldn’t be fighting. Peanuts, for example, or other foodstuffs.
One study has found a connection between sleep deprivation and allergies. This study looked at people with peanut allergies who were sleep-deprived and found that they were more prone to have an allergic reaction. In fact, the “peanut threshold” that triggered these reactions was lowered by almost half (45%).
Part of the reasoning here is that we believe there’s a connection between the circadian rhythm and how the body reacts to certain allergens. Disrupting the balance of the circadian rhythm, and therefore the balance of the immune system may make these reactions more frequent and more intense.
It’s quite obvious by now how poor sleep can have wide-ranging negative effects on your health. Short-term health, long-term health, and overall wellness are all impacted by skimping on sleep. However, the relationship between sleep and your immune system is bidirectional, meaning that it’s just not your sleep that affects your immune function.
Getting an infection will trigger various responses from your body, one of which often includes fatigue and sleepiness. Makes sense, right? Often when we’re sick, we spend a lot of time in bed.
However, pathogens can also change the ways in which we sleep—specifically, the different stages of sleep.
For example, the higher body temperature that comes with a fever makes the body more inhospitable to foreign invaders. Some researchers believe that the sleep changes which occur when we’re sick are specifically designed to induce fevers.
This is due in part to an increased amount of time in non-rapid eye movement (NREM) sleep—also called “deep sleep.” This deep sleep is when our bodies significantly reduce their energy expenditure, most likely allowing for greater resource usage by the immune system. However, deep sleep plays another role when it comes to fevers.
Shivering is an important part of elevating our body temperature, but it can’t happen during rapid eye movement (REM) sleep due to our muscles losing strength (muscle atonia). So, our bodies pretty much get rid of REM sleep when we’re sick, opting instead for more deep sleep in order to keep the ability to shiver. Interestingly, this is also the reason some people get fever dreams. Since REM sleep is fragmented and diminished, more nightmares might occur for some individuals.
Hygiene isn’t all about smelling good. When it comes to sleep, it can both deeply impact your mental wellbeing and your overall health.
The key, however, is understanding whether better sleep is within our control. Put otherwise, are we choosing to make poor decisions or is there some kind of underlying issues keeping us from sleeping? Choices are more easily fixed since the latter is usually out of our control. Sleep disorders, such as sleep apnea, can keep us from getting a good night’s sleep. Certain sleep medicine can lower our susceptibility to sleep loss, allowing for better immunological function.
However, these are things that are best discussed with a doctor. It’s much easier to solve poor sleep when it’s because of habits.
So, what choices can we make to ensure adequate sleep?
Sleep is almost synonymous with relaxation, so it makes sense that stress is going to get in the way of peaceful sleep.
Some things in our lives can’t be helped—like a stressful job or a stressful situation. While it’s easy to say that one should get out of these situations to get better sleep, it’s much more difficult to do. However, there are strategies to at least help your path to higher quality Z's.
Winding down for an hour before bed is a fantastic way to practice good sleep hygiene. This means not staring into screens or doing any work, but instead winding down with a relaxing activity or a good book.
Activities during the day like exercise, yoga, or meditation, can also help to put us in a better frame of mind for sleep. In particular, exercise that offers enough exertion can tire us out enough to put us to bed without trying very hard. Furthermore, all of these activities will have positive effects on our mental wellbeing as much as our physical.
Cultivating a routine is one of the best things you can do—for sleep, or otherwise. It will help you control potential sleep disturbances and improve the quality of your sleep.
Keeping a consistent sleep time and wake-up time on a day to day basis will put your best foot forward when it comes to sticking to a schedule. Your sleep stages will be balanced, and your antibody response will thank you. And that’s not even mentioning the productivity-boost you’ll experience.
Healthy eating, as always, will be a cornerstone in any holistic approach to wellness. Getting a couple of McDoubles right before you hit the hay isn’t going to make you feel (or look) good. Healthy, immune-boosting foods are the way to go.
And if you want to get an edge on your sleep, or you need some extra help getting in those Zs due to life circumstances, there are also effective supplements you can try. While a supplement won’t serve as a magic bullet for your sleep troubles, it can prove invaluable if all you need is that extra little something.