HOUSTON (KIAH) Adults who cut back on sleep for six weeks could be running the risk of altering their immune system, according to a report from the National Institutes of Health. The study found catching up on sleep does not reverse this effect.

In a study published in the Journal of Experimental Medicine, researchers enrolled 14 adults in a sleep study where they had enough sleep (at least 7 and half hours) for six weeks and had their blood drawn to be analyzed. After a six week break, the participants sleep for only six hours. Their blood was analyzed once again.

By the fifth and sixth weeks of morning and afternoon blood draws during the sleep-deprived weeks, researchers found that when adults didn’t get enough sleep, they had higher levels of a certain white blood cell in their blood in the afternoon. They also had higher numbers of immune stem cells in the blood and evidence of immune activation.

“The stem cells have been imprinted, or genetically altered, under the influence of sleep restriction,” said Filip K. Swirski, Ph.D., a senior study author and director of the Cardiovascular Research Institute at Icahn School of Medicine at Mount Sinai, New York City. “The change isn’t permanent, but they continue to self-replicate at a higher rate for weeks.”

This higher production of these immune cells has been linked to increased risks for cardiovascular disease, inflammatory disorders, and neurodegenerative diseases.

“Sleep impacts optimal functioning of nearly every cell and organ in the body,” said Marishka K. Brown, Ph.D., director of the National Center on Sleep Disorders Research, located within the National Heart, Lung, and Blood Institute (NHLBI). “The mechanistic insight from this study supports findings from larger population studies, which have shown that sleep can have a protective effect against a variety of conditions, including heart disease, cancer, and dementia.”

The study authors said their findings also underscored the importance of establishing sound sleep patterns early in life, which may reduce the severity of other inflammatory conditions such as sepsis. Most adults should get 7-8 hours of uninterrupted sleep each night. Older adults need about 7-9 hours, while children ages 11-17 need about 8-10 hours.