A new study has found that chronic sleep deprivation increased the production of immune cells related to inflammation in healthy adults. It also altered the DNA of immune cells, which is what a recent study showed.
Cameron McAlpine (study coauthor), an assistant professor of neuroscience at the Icahn school of medicine at Mount Sinai in New York City, said that not only was the immune cell count elevated but also that they might have been wired and programmed differently after six weeks of sleep restriction.
These two factors can potentially make someone more susceptible to diseases such as cardiovascular disease.
Experts agree that a certain level of immune system inflammation is essential for the body’s ability to heal wounds and fight infection. However, an overactive immune system can lead to chronic diseases and autoimmune disorders.
The study was published in the Journal of Experimental Medicine on September 21st, 2009.
Steven Malin, associate professor at Rutgers University’s department of kinesiology & health in New Jersey, said that “this work aligns with the views in the field which sleep restriction can increase risk of type 2 diabetes or hypertension.”
Malin, who wasn’t involved in the study, said that “practically speaking, these findings support ideas for developing good sleep habits so that most of your time you are getting adequate rest.”
Good sleep heals
The body must go through four stages of sleeping each night in order to be healthy. The body begins to slow down its rhythms during the first and second stages. This prepares us to enter the third stage, which is deep, slow-wave sleep. It’s where the body literally repairs itself at a cellular level.
Rapid eye movement sleep (REM) is the last stage of dreaming. Research has shown that REM sleep is crucial for memory and cognitive function. It can also lead to poor outcomes and early death.
However, research over many years has shown that sleep, particularly the most profound and healing, can boost immune function.
According to the US Centers for Disease Control and Prevention, each sleep cycle lasts approximately 90 minutes. Most adults require seven to eight hours of uninterrupted sleep to get restorative sleep.
Inflammation signs and symptoms are increasing
The study involved 14 healthy, young people who had no sleep problems. McAlpine stated that the study’s duration was quite long, which gave it strength.
He said that many sleep studies only last for a day or two, and then it can take up to a week. “But very few studies examine the effects of sleep over a prolonged period of six weeks. This is what we did.”
The wrist accelerometers were worn by all participants in the study, which allowed researchers to track their sleep quality over 24 hours. Each participant slept the recommended seven to eight hours per night for adults during the first six weeks. They slept for 90 minutes less each night over the next six weeks.
Each six-week cycle ended with blood drawn in the morning and evening to check for immune cell reactivity. People who slept well did not experience any adverse effects. After six weeks of sleep restriction, blood tests showed an increase in one type of immune cell when blood was taken in the evenings.
McAlpine stated that “this defect of sleep restriction was very specific for one type of immune cell called a monocyte, whereas other immune cells did not respond.” This is an indication of inflammation.
After a long period of sleep deprivation, blood tests revealed epigenetic changes in the monocyte immune cells. According to the National Human Genome Research Institute, epigenetics are proteins or chemicals that sit on top of each gene like freckles, waiting for the gene to “what to say, where to go it, and when,” respectively. The epigenome switches genes on or off, often depending on environmental triggers and human behavior such as smoking, chronic lack of sleep, and eating an inflammatory diet.
Malin stated that sleep restriction can alter genes that are related to inflammation and other factors. This modification increases the risk that immune cells will become more inflammatory. Although the study did not provide clinical or functional measures to confirm disease risk it laid (the) foundation for future research to examine these mechanisms.
Epigenes can also be turned on or off. Would the immune function change remain even after subjects go back to sleep for full nights? This outcome was not possible to test in humans. However, the researchers conducted additional studies on mice and found interesting results.
Are these changes permanent?
The immune activity of the mice that were sleep-deprived mirrored the human immune system. Immune cell production was higher and epigenetic changes in immune cell DNA were observed. The mice were allowed to sleep for 10 weeks before being tested again.
Researchers found that the DNA changes were not corrected and that the immune system was still overproducing, which made the mice more vulnerable to disease and inflammation.
McAlpine stated that “our findings suggest that sleep recuperation is not able fully to reverse the effects on poor-quality sleep in mice” and that his laboratory is still working with people to determine if the results will apply to humans. Note: Mice studies are not always translated.
“This study begins the identification of biological mechanisms that link long-term sleep and immunological health. This observation is crucial because it is another important observation that sleep reduces inflammation, and that interruption to sleep increases inflammation,” Filip Swirski (director of the Cardiovascular Research Institute at Icahn Mount Sinai), said in a statement.
“This study emphasizes the importance for adults to sleep seven to eight hours per night to prevent inflammation and disease, particularly in those with underlying medical conditions.”