Chronic sleep deprivation in a small group of healthy adults increased the production of immune cells linked to inflammation while also altering the DNA of immune cells, a new study found.
“Not only were the number of immune cells elevated, but they may be wired and programmed differently at the end of six weeks of sleep restriction,” said study co-author Cameron McAlpine, an assistant professor of cardiology and neuroscience at the Icahn. Mount Sinai School of Medicine in New York City.
“Together, these two factors could potentially predispose someone to conditions like cardiovascular disease.”
A certain amount of immune system inflammation is necessary for the body to fight infection and heal wounds, but an overactive immune system can be harmful and increase the risk of autoimmune disorders and chronic diseases, experts say.
“This work aligns with views in the field that sleep restriction may increase the risk of type 2 diabetes and hypertension,” said Steven Malin, an associate professor in the department of kinesiology and health at Rutgers University in New Jersey. .
“In practice, then, these findings support ideas for developing good sleep habits, so that most of the time you get enough sleep,” added Malin, who was not involved in the study.
To be healthy, the body needs to go through four stages of sleep several times each night. During the first and second stages, the body begins to slow down its rhythms. Doing so sets us up for stage three: deep, slow-wave sleep in which the body literally restores itself at the cellular level, repairing the damage caused by the day’s wear and tear and consolidating memories into long-term storage.
Rapid eye movement sleep, called REM sleep, is the final stage in which we dream. Studies have shown that a lack of REM sleep can lead to memory deficits and poor cognitive outcomes. as well as heart and other chronic diseases and a early death.
Secondly, years of research has found that sleep, especially the deepest, most healing sleep, stimulates immune function.
Since each sleep cycle lasts about 90 minutes, most adults need seven to eight hours of relatively uninterrupted sleep to achieve restful sleep, according to the US Centers for Disease Control and Prevention..
The study was small and involved 14 young, healthy people with no sleep problems. But the length of the study was also quite long, which gave it strength, McAlpine said.
“A lot of sleep studies are one day, two days, maybe a week or two,” he said. “But there are very few that look at the influence of sleep over a period as long as six weeks, which is what we did.”
Everyone in the studio. They used wrist accelerometers, which allowed the researchers to track the quality and duration of their sleep during each 24-hour period. During the first six weeks, each study participant got the seven to eight hours of sleep that the CDC recommends for adults. For the next six weeks, they cut back on sleep by 90 minutes each night.
At the end of each six-week cycle, blood was drawn in the morning and evening and tested for immune cell reactivity. No negative changes were found in people who got enough sleep. However, after study participants spent six weeks with sleep restriction, blood tests found an increase in a certain type of immune cell when blood was drawn at night.
“This sleep restriction defect was very specific to a type of immune cell called a monocyte, while other immune cells were unresponsive,” McAlpine said. “This is a sign of inflammation.”
Blood tests also found epigenetic changes within monocyte immune cells after the long period of sleep deprivation. Epigenes are proteins and chemicals that sit like freckles on each gene, waiting to tell the gene “what to do, where to do it, and when to do it,” according to the National Human Genome Research Institute. The epigenome literally turns genes on and off, often based on environmental triggers and human behaviors such as smoking, following an inflammatory diet, or suffering from chronic lack of sleep.
“The results suggest that factors that can modify the gene expression of inflammation-related proteins, known as the epigenome, are modified by sleep restriction,” Malin said. “This modification increases the risk that the immune cells will be more inflammatory in nature. The study did not perform functional or clinical measures to confirm disease risk, but it lays the groundwork for future studies that consider these mechanisms.”
Epigenes can be turned on and off, so would the change in immune function be maintained after the study subjects went back to sleep through the night? The study was unable to investigate that outcome in humans. But the researchers did additional studies in mice that produced interesting results.
Immune activity in the sleep-deprived mice mirrored that in humans: immune cell production increased, and epigenetic changes were observed in the DNA of immune cells. In these studies, the mice were allowed to sleep well for 10 weeks before being tested again.
Despite getting enough sleep over a long period of time, the researchers found that the DNA changes remained and the immune system continued to overproduce, making the mice more susceptible to inflammation and disease.
“Our findings suggest that sleep catch-up cannot completely reverse the effects of poor-quality sleep. in mice,” McAlpine said, adding that his lab is continuing to work with people to see if that result translates to humans. (Note: mouse studies often do not translate.)
“This study begins to identify the biological mechanisms that link sleep and long-term immune health. This is important because it is another key observation that sleep reduces inflammation and, conversely, sleep disruption increases inflammation,” lead author Filip Swirski, director of the Cardiovascular Research Institute at Icahn Mount, said in a statement. Sinai.
“This work emphasizes the importance of adults getting consistent seven to eight hours of sleep a day to help prevent inflammation and disease, especially for those with underlying medical conditions.”