One of the frequently overlooked tools of fighting infection is simply getting more sleep. Not only does sleep help you get over an infection, it helps your immune system remember how to fight the infectious microorganism the next time you encounter it.
Scientists have known for over a century that sleep, particularly slow-wave sleep, also known as deep sleep, is important for helping the brain assemble fragile short-term memories into durable long-term memories. More recently, scientists have discovered that deep sleep is key to the immune system's ability to form strong immunological memories of previously encountered pathogens.
"While it has been known for a long time that sleep supports long-term memory formation in the psychological domain, the idea that long-term memory formation is a function of sleep effective in all organismic systems is in our view entirely new," says researcher Dr. Jan Born of the University of Tübingen in Germany. "We consider our approach toward a unifying concept of biological long-term memory formation, in which sleep plays a critical role, a new development in sleep research and memory research."
How The Immune System Remembers Disease-Causing Microbes
Our immune systems "remember" an encounter with a virus or a bacterium by collecting fragments of it, and then using those fragments to create a memory T cell. These specialized white blood cells store only the tiniest fragment of the surface of a disease-causing organism needed to activate a response.
Once the memory T cell has been created, it can respond not just to the same organism entering the body again, but also to similar bacteria or viruses.
The Immune System Needs Deep Sleep To Make Memory T Cells
Scientists first noticed the connection between deep sleep and immunity when they were looking for factors that make vaccinations more or less effective. Researchers observed that slow-wave deep sleep on the night after receiving a vaccination is associated with better disease protection. Just as the brain needs sleep to form complex long-term memories from recent events, the immune system needs sleep to form a complex series of proteins that make a memory T cell responsive to a germ.
The researchers working with Dr. Born speculate that if we don't sleep after a vaccination or an infection, our immune systems don't focus on the right parts of the bacterium or virus causing the disease. Many "bugs" are capable of mutating proteins to escape immune responses. Our immune system typically doesn't have to work quite as hard to fight infection during deep sleep. If we get deep sleep, we have more antigen-presenting cells that are free to present parts of the germ to antigen-recognizing cells, which can then form a "memory" of the encounter. If we don't get deep sleep, our immune system has to work harder to fight the infection while it is still in the body, and it does not get a chance for antigen-presenting cells to work with antigen-recognizing cells. The antigen-presenting cells are too busy fighting the infection to form a memory of it by working with the antigen-recognizing cells.
Born believes that understanding the connection between deep sleep and immunological memory may be the key to making successful vaccinations against HIV, malaria, and tuberculosis.
If it is possible to reach the antigen-presenting cells during sleep, or to recreate the conditions that enable them to cooperate with other parts of the immune system, then vaccines to conquer these plagues may be possible. The only reason to get good sleep when you have an infection, however, is not so vaccines will work better.
Sleep Your Infections Away
Most of our mothers taught us that if we don't get enough sleep, we will get sick. Dr. Diwakar Balachandran, director of the Sleep Center at the University of Texas M.D. Anderson Cancer Center in Houston confirms that what our mothers and grandmothers taught us is scientifically verified, at least for colds, flu, and HIV.
The relationship between getting enough sleep and staying infection-free is at least two-fold:
- When we don't get enough sleep, our immune systems don't fight disease as effectively.
- Also, when we don't get enough sleep, our bodies produce more inflammation.
It's not just that you are more likely to catch a cold or flu (or HIV) when you are sleep-deprived. Your immune system will use more inflammation to fight it. In the case of colds and flu, this means more aches and pains, more runny nose, more phlegm, and more fever. However, there is also an important relationship between sleep and the effectiveness of fever in fighting disease.
Fever "cooks" infectious microorganisms. However, the germs that cause infections have to be "primed" so that they are killed by fever (or at least stop reproducing so rapidly so the immune system can more easily deal with them). This priming process only occurs during sleep.
Sleep isn't just important for fighting infection. It is also important for fighting heart disease. The less sleep you get, the more inflammation your body generates.
People who consistently get less than seven hours of sleep every night generate high levels of C-reactive protein, a marker of inflammation, an indicator that cholesterol plaques may burst and block levels or that clotting factors may be activated to generate clots that interfere with circulation to the heart, brain, lungs, or colon.
How Much Sleep Do You Really Need?
Seven hours seems to be a minimum. More than nine hours indicates that some sleep disturbance is a problem. People who have sleep apnea wake up dozens or even hundreds of times every night just for a second or two, not fully waking up, but not getting deep, restorative sleep, either. They don't just feel tired all the time. They are also much more susceptible to infections.
What Can You Do To Get More Sleep?
For many people, the most important thing to do is to turn off the computer. Constantly checking the Internet ruins sleep. It is also important to turn off lights. This includes the TV, of course, but it also includes shutting out outdoor light and even night lights. The way the brain works, any exposure to blue light stops the production of the sleep hormone melatonin.
Even when the eyes are closed, the brain is sensitive to blue light. It's best to sleep in a room that is totally dark. Simply turning off the lights may be surprisingly helpful in overcoming and preventing infection.
- Cell Press. Sleep may strengthen long-term memories in the immune system. Eureka Alert System. 29 September 2015.
- Photo courtesy of peasap: www.flickr.com/photos/peasap/2561252071/
- Photo courtesy of rlcalamusa4156/: www.flickr.com/photos/rlcalamusa4156/6041578611
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