Topic: Sleep and Immune Function
Source: European Journal of Physiology (2012)
Lifestyle Medicine Update No 158 (April 9, 2020)
with Dr. James Meschino
In this update, I want to highlight the importance of regular and adequate sleep on immune health. An often overlooked aspect of supporting the body’s immune system is the need to get adequate sleep on a regular basis. Studies are very clear that sleep deprivation weakens our body’s ability to fight off viral, bacterial and other infections. A major review paper on sleep and the immune system, published in the European Journal of Physiology, consolidated the world-wide evidence showing that sleep deprivation, or sleep curtailment as they describe it, leads to chronic low-grade inflammation and immunodeficiency = a weak immune system. The review paper highlights studies showing that chronic sleep loss reduces the body’s production of antibodies after the administration of the flu vaccine and increases the risk of developing the common cold, which is caused by numerous different rhino, carona, and other viruses. Animal studies have also shown that sleep deprivation significantly reduces immune function, inhibiting the ability of animals to fight off experimental viral infections.
So, how does sleep help to optimize immune function? During sleep, there is a decrease in the release and circulating levels of cortisol, adrenaline and noradrenaline, and a concomitant increase in circulating growth hormone, prolactin, and melatonin. This critically important hormonal shift prompts many T-lymphocytes to emerge from the bone marrow, where they are produced, and circulate throughout the body, often taking up residence in the lymph glands and other immune tissue of the body. Once in the lymph tissue, the T-lymphocytes await the arrival of antigen-presenting immune cells that prompt these T-lymphocytes to mount a specific attack against a virus or other pathogenic agent that is trying to infect the body. Essentially what happens is that certain immune cells known as antigen-presenting cells that are part of our innate immune system, like macrophages, dendritic cells, and neutrophils, identify a foreign invader like a virus. They then gobble up the virus and display the viruses’ spiky extensions on their own surface and bring this information to the T-lymphocytes that are awaiting their arrival in the lymph glands. Once the T-lymphocytes are presented with the viruses’ antigenic spiky extensions, the T-lymphocytes kick into gear and mount a full-fledged attack against the viral invader.
This response by the T-lymphocytes is known as adaptive immunity and this aspect of immune function is critical to preventing and fighting off viral and other infections. It is also adaptive immunity, coordinated by T-lymphocytes, that enables the body to produce antibodies to kill viruses and to retain some of these antibodies once the fight is over for future use if necessary. In other words, the body retains the ability to quickly make antibodies against that particular virus or bacteria, should it show up again in the body at some point in the future. It’s a well-functioning adaptive immune system, involving T-lymphocytes, that enable vaccinations to work, as the T-lymphocytes provide instructions to other immune cells to make a specific antibody to fight off smallpox, or measles or polio, etc. , after which the immune system retains memory cells that can quickly generate these antibodies should we become exposed to these pathogenic microbes at some point in the future. Needless to say, the function of our T-lymphocytes is crucial to optimal immune function. And the best way to keep your T-lymphocytes available, primed and ready to go, is to get adequate sleep on a regular basis. Proper nutrition is important, moderate exercise is important, taking certain supplements can support immune function, of course, avoiding contact with infectious viruses is critical, but getting enough sleep, and having a regular sleep-wake cycle should also be high on your priority list when it comes to keeping your immune system in the best possible shape to fight off an infectious virus, bacteria, fungus etc. Optimal immune function, including T-lymphocyte function, is also critical in preventing cancer by the way. So, get the sleep your body needs to feel rested and fully recharged on a daily basis.
I have included the reference for this information in the text below.
Besedovsky L, Lange T, Born J. Sleep and immune function. European Journal of Physiology (2012) 463:121-137
Eat Smart, Live Well, Look Great,
Dr. James Meschino