How lack of sleep can harm immune stem cells

A new study has highlighted one-way insufficient sleep can harm your immune system, making you more vulnerable to infections and inflammatory disease by damaging your body's hematopoietic stem cells.

"This study begins to identify the biological mechanisms that link sleep and immunological health over the long-term," explained lead author Filip Swirski, according to New Atlas.

"It shows that in humans and mice, disrupted sleep has a profound influence on the programming of immune cells and rate of their production, causing them to lose their protective effects and actually make infections worse - and these changes are long-lasting," he said.

The new research focused on a lifelong mechanism called hematopoiesis, which primarily takes place in the bone marrow. This is the process by which your body regenerates new blood cells, some of which are immune cells, or monocytes.

So the big question the research was investigating was how sleep influences hematopoiesis, and more specifically monocyte production. The first step was the recruitment of 14 healthy adults for a sleep experiment.

The cohort was tasked with getting six weeks of healthy sleep, a minimum of 7.5 hours per night. After a break, the cohort then spent six weeks reducing their sleep by around 90 minutes, to roughly six hours per night. Blood samples were taken at a variety of points across the experiment.

The researchers found just six weeks of sleep disruption led to significant changes in the participants' hematopoietic stem and progenitor cells (HSPCs), those precursor stem cells that eventually become monocytes. The DNA structure of the sleep-deprived HSPCs was altered to promote inflammatory states and there were more of them proliferating in the blood.

"The stem cells have been imprinted, or genetically altered, under the influence of sleep restriction," Swirski said.

The researchers then moved to mouse models to further explore the effect of sleep on immune stem cells. The findings from the human tests were replicated in the animal studies but the researchers also found signals suggesting this sleep deprivation damage to stem cells may not return to normal when better sleep practices resume.

The mice continued to produce excessive volumes of damaged immune stem cells after returning to standard sleep patterns. Cameron McAlpine, the lead investigator on the study, said this suggests insufficient sleep may play a role in speeding up the immune ageing process.

"Our findings suggest that sleep recovery is not able to fully reverse the effects of poor-quality sleep," said McAlpine. "We can detect a molecular imprint of insufficient sleep in immune stem cells, even after weeks of recovery sleep. This molecular imprint can cause the cells to respond in inappropriate ways leading to inflammation and disease."