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.