Source: Mount Sinai Hospital
Chronic, insufficient sleep can negatively affect immune cells, which can lead to inflammatory disorders and cardiovascular disease, according to a new study from the Icahn School of Medicine at Mount Sinai. More specifically, consistently losing an hour and a half of sleep per night can increase your risk.
The research, published on September 21 in the Journal of Experimental Medicine, is the first to show that sleep alters the structure of DNA within immune stem cells that produce white blood cells, also known as immune cells, and this can have a lasting impact on inflammation and contribute to to inflammatory diseases.
Immune cells fight infection, but if the number of these cells increases too much, they overreact and cause inflammation. The study is also the first to show that catching up doesn’t reverse the effects of disrupted sleep.
“This study begins to identify the biological mechanisms that link sleep and long-term immune health. It shows that in humans and mice, sleep disruption has a profound influence on the programming of immune cells and the speed of their production, causing them to lose their protective effects and actually make infections worse, and these changes are long-lasting.
“This is important because it’s another key observation that sleep reduces inflammation, and conversely, that sleep disruption increases inflammation,” says lead author Filip Swirski, PhD, director of the Cardiovascular Research Institute of ‘Icahn Mount Sinai.
“This work emphasizes the importance of adults getting a consistent seven to eight hours of sleep a day to help prevent inflammation and disease, especially for those with underlying medical conditions.”
A team of researchers looked at 14 healthy adults who regularly sleep eight hours a night. First, the researchers monitored them sleeping at least eight hours a night for six weeks. They drew his blood and analyzed his immune cells. The same group of adults then reduced their sleep time by 90 minutes each night for six weeks, and their blood and immune cells were reanalyzed.
At the end of the study, the researchers compared the blood and cell samples from the full night and the restricted sleep periods.
All participants had significant changes in their immune cells (also known as hematopoietic cells) due to lack of sleep: there were more of them and the structure of the DNA was altered. After six weeks of sleep restriction, they had higher numbers of immune cells.
The researchers also analyzed sleep in mouse models. Groups of mice were either allowed to sleep undisturbed or had sleep fragmentation, where they woke up throughout the night for 16 weeks. The sleep-fragmented mice were then put through uninterrupted sleep recovery for ten weeks.
The researchers took immune stem cells and immune cells from mice during these fragmented, undisturbed recovery phases of sleep, analyzed them, and compared them at the end of the experiment.
The results in mice were consistent with the results in humans. They showed that all the mice with fragmented sleep had significant changes in their immune stem cells, producing greater numbers of immune cells, and also showed evidence of rewiring and reprogramming.
A remarkable discovery from the group of mice was that even after recovery from sleep, the immune stem cells retained this wiring structure and continued to produce additional white blood cells, making the mice susceptible to inflammation and the disease
“Our results suggest that recovery sleep is not able to completely reverse the effects of poor quality sleep. We can detect a molecular imprint of insufficient sleep in immune stem cells, even after weeks of recovery sleep .
“This molecular imprint can cause cells to respond in inappropriate ways that lead to inflammation and disease,” says co-investigator Cameron McAlpine, PhD, assistant professor of Medicine (cardiology) at Icahn Mount Sinai.
“It was surprising to find that not all groups of stem cells responded to sleep deprivation in the same way. There were some groups of stem cells that proliferated and grew in number, while others make smaller. This reduction in the overall diversity and aging of the immune stem cell population is a major contributor to inflammatory diseases and cardiovascular disease.”
Funding: The National Heart, Lung, and Blood Institute and the National Center for Advancing Translational Sciences, part of the National Institutes of Health, helped fund this study.
About this research news about sleep and inflammation
Author: Ilana Nikravesh
Source: Mount Sinai Hospital
Contact: Ilana Nikravesh – Mount Sinai Hospital
Image: The image is in the public domain
Original Research: Findings will appear in Journal of Experimental Medicine