Over-tired and under-rested? New research on sleep and the immune system suggests that you may be at greater risk of illness.

Researchers in chronobiology have long realized that sleep can affect the memory of information, facts and past events. However, a new study suggests that sleep may also affect a very different kind of memory: immune memory.

What Is Immune Memory?

Many people have had chicken pox or other childhood illnesses. These illnesses are associated with childhood because most people will only catch them once. The reason for this, and the efficacy of vaccines as well, is long-term immune memory.

When a bacteria, virus or other invader enters your body, specialized immune cells engulf it. These cells then express parts of the invader’s cell wall, called antigens, on their surface. Memory T cells bind to these macrophages and recognize these antigens as invaders. In a person with a healthy immune system, this type of memory will last a lifetime. Every time this same type of bacteria or virus enters your body, these memory T cells will immediately recognize the antigens on their cell surface and stimulate the immune system to eradicate the invader before it can cause illness.

Sleep and the Immune System

Researchers have recognized that sleep, or lack thereof, can affect the immune system. While the exact mechanism was unknown, the relationship was clear. People who are sleep deprived are more than four times as likely to catch the common cold when exposed, as well as influenza and other infectious diseases. Physicians and scientists were not sure whether this was due to a general decline in health when sleep deprived or if there is a concrete mechanism.

Can Sleep Keep You From Getting Sick?

The link between sleep and the immune system is unclear. However, a new theory is shedding light on one mechanism for circadian rhythm’s effect. New research suggests that deep sleep, also known as slow wave sleep, increases numbers of memory T cells in our bodies. Over months of regular sleep, this can create a measurably higher number of these protective immune cells. In addition, these cells are more effective when people get adequate sleep. When people are well-rested, memory T cells are more likely to store “gist information” that will help them to better identify illness-causing pathogens in the future.

Memory T cells are not the only necessary component of a healthy immune system, so this new discovery will not overhaul medical treatment as a whole. However, this is one valuable insight into the way circadian rhythm and immunity are linked. This may offer a new approach to the prevention and treatment of viruses and bacteria that mutate regularly, as memory T cells may actually be able to respond better to these invaders when we are well-rested over a long period of time. Researchers are already discussing incorporating sleep into trials for vaccines for HIV and other devastating illnesses.

Sleep is an important part of whole body health. Not only will a good night’s rest make you feel better, it will likely also make you healthier as well.