Why Sleep is Important for the Immune System and Gut

Health Professional
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It is well known that lack of sleep is associated with many diseases, including heart disease, diabetes, infections, cancer, neurological disorders, anxiety, depression and gastrointestinal disorders. Changes in sleep patterns affect the central nervous system, as well as the immune system, which in turn has an effect on different organ systems in the body. For example, studies have shown some gastrointestinal disorders, namely irritable bowel syndrome (IBS), may be associated with an increase in the amount of REM sleep, or the fourth part of the sleep cycle when we have the most vivid dreams. At this point, however, there have not been any negative consequences to such changes in sleep patterns. On the other hand, in Crohn’s disease or ulcerative colitis, long-term activation of the immune response may result in impaired sleep, poor quality of sleep or other sleep, and vice versa. Poor sleep may worsen disease.

Sleep and the immune system

During sleep, the immune system produces special proteins called cytokines. These play a role in the inflammatory response, either by increasing the inflammatory response or blocking it, depending on our bodies’ needs. Cytokines help promote sleep, fight infection or block inflammation in chronic inflammatory diseases (example: Crohn’s disease or ulcerative colitis). Insufficient sleep can significantly alter the cytokines produced resulting in a decrease in protective effects. In addition, infection-fighting cells decrease in states of sleep deprivation, which makes it harder for your body to fight infection. Ultimately, this results in an increase in the inflammatory response or a persistently revved up immune system. The production of a hormone called cortisol increases in times of stress or inflammation. This, in turn, causes an increase in inflammatory cytokines, and the vicious cycle continues.

The immune system and the gut

The immune system plays a major role in many gastrointestinal disorders, including Crohn’s disease, ulcerative colitis, irritable bowel syndrome, small intestinal bacterial overgrowth and many others. In these disorders, the gut inflammatory response is chronically active for differing reasons, resulting in abnormal levels of cytokines, cortisol and changes in the gut flora innate to the gastrointestinal tract or microbiome.

Sleep affects the gut, AND the gut affects sleep

Chronic, or long-term, activation of the immune response in the gut can result in sleep disturbances or sleep disorders. In some disorders, such as small intestinal bacterial overgrowth, inflammation is caused by abnormalities of the microbiome or dysbiosis. The gut barrier function becomes compromised, leading to translocation of bacteria and pathogens into blood circulation, commonly referred to as leaky-gut, triggering the immune response. The hallmark for inflammatory bowel disease (IBD) is a persistently active immune response in the lining of the gut, also affecting gut wall barrier function and increasing cytokines and cortisol levels, which, taken together, can result in sleep disturbances.

The reverse can occur as well, however. Poor or inadequate sleep causes stress to the body, increases the inflammatory response through production of abnormal levels of cytokines and cortisol, which can lead to worsening of gastrointestinal disorders or trigger disease flares.

More is not always better

It is recommended that the average adult get seven to eight hours of sleep per night. Sleeping any more than nine hours may actually have a negative impact on overall sleep and is not recommended. Too much sleep can cause poor quality of sleep or trouble falling asleep or staying asleep. If you are having problems sleeping, talk to your doctor. Other serious underlying medical conditions could be the cause for sleep disturbances, which should not simply be treated with medications that induce sleep. Once other medical conditions have been ruled out as the cause for sleeping problems, work with your doctor on sleep hygiene measures to increase and improve your sleep.