(CNN) –– 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 this class of cells, a new study found.
“Not only were the number of immune cells elevated, but they may have been wired and programmed differently at the end of six weeks of sleep deprivation,” said study co-author Cameron McAlpine, an assistant professor of cardiology and neuroscience at the Mount Sinai Icahn School of Medicine in New York City.
“Combined, these two factors could potentially predispose someone to diseases such as cardiovascular disease,” he added.
A certain amount of immune system inflammation is needed for the body to fight infections and heal wounds, but an overactive immune system can do harm and increase the risk of autoimmune disorders and chronic diseases, experts warn.
The study was published September 21 in the journal Journal of Experimental Medicine.
“This work aligns with perspectives in the field that sleep deprivation 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. .
“So pretty much, these findings support ideas to develop good sleep habits, so most of the time you sleep adequately,” added Malin, who was not involved in the study.
sleep well healthy
To stay healthy, the body needs to go through four stages of sleep multiple times each night. During the first and second stages, the body begins to slow down its rhythms. That sets us up for the third phase: deep, slow-wave sleep, in which the body literally restores itself at the cellular level, repairing the damage of the day’s wear and tear and consolidating memories into long-term storage.
Rapid eye movement sleep, known as REM, is the final stage of dreaming. Studies have shown that a lack of REM sleep can lead to memory deficits and poor cognitive outcomes, as well as heart disease and other chronic conditions. Even to a premature death.
On the other hand, years of research have found that sleep, especially the deepest, most healing sleep, stimulates immune function.
Since each sleep cycle lasts about 90 minutes, most adults need a relatively uninterrupted seven to eight hours of sleep to achieve restful sleep, according to the US Centers for Disease Control and Prevention (CDC, for its acronym in English).
An increase in signs of inflammation
The study, which was small, looked at 14 young, healthy people with no sleep problems. However, the duration of the investigation was 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 long period of six weeks, which is what we did,” she added.
All study participants wore wrist accelerometers, which allowed the researchers to monitor the quality and duration of sleep during each 24-hour period. In the first six weeks, each study participant got a full seven to eight hours of sleep—just the amount the CDC recommends for adults. However, over the next six weeks, sleep dropped to 90 minutes a night.
After each six-week cycle, the participants had their blood drawn in the morning and at night, and their immune cells were tested for reactivity. No negative changes were found in people who got enough sleep. However, after study participants spent six weeks on sleep restriction, blood tests detected an increase in a certain type of immune cell in samples drawn at night.
“This sleep deprivation defect was very specific to a type of immune cell called a monocyte, while other immune cells did not respond,” McAlpine explained. “This is a sign of inflammation.”
Blood tests also found epigenetic changes within the monocyte cells after the long period of sleep deprivation. Epigenomes are proteins and chemicals that sit like freckles on each gene, waiting to tell it “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 chronic sleep deprivation.
“The results suggest that factors that can modify gene expression of inflammation-related proteins, known as the epigenome, are modified by sleep restriction,” Malin explained. “This change increases the risk of immune cells being more inflammatory in nature. The study did not perform functional or clinical measures to confirm disease risk, but it does lay the groundwork for future studies looking at these mechanisms,” she added.
Epigenomes can be turned on and off, so would the change in immune function be sustained after the study subjects returned to a full night’s sleep? The study was unable to investigate that outcome in humans. But the researchers carried out additional studies in mice that left interesting results.
Are the changes permanent?
The immune activity in the sleep-deprived mice mirrored that in humans: immune cell production increased, and epigenetic changes in the cells’ DNA were observed. 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, 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 catching up on sleep may not completely reverse the effects of poor sleep in mice,” McAlpine said, adding that his lab continues to work with people to see if that result carries over to humans as well. (Note: mouse studies are often not mirrored in humans).
“This study begins to identify the biological mechanisms that link sleep to 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, explained 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,” he concluded.