Anxiety and insomnia linked to sharp drops in key immune cells

Anxiety disorder and insomnia are both known to interfere with healthy immune activity. With these conditions becoming more common, researchers in Saudi Arabia investigated how they relate to NK cell levels in young female students. Their findings were published in Frontiers in Immunology.

"We found that in students with insomnia symptoms, count and percentage of total NK cells and their sub-populations were declined," said first author Dr. Renad Alhamawi, an assistant professor of immunology and immunotherapy at Taibah University. "Students with general anxiety symptoms, on the other hand, had a lower percentage and number of circulatory NK cells and their sub-populations, compared to symptom-free students."

Study Design and Student Health Profiles

60 female students aged 17 to 23 took part in the research. Each participant completed three questionnaires on sociodemographic information and on symptoms related to anxiety and insomnia. Reports of anxiety and sleep disturbance were self-described. According to the surveys, about 53 percent of the students experienced sleep difficulties consistent with insomnia, and 75 percent reported anxiety symptoms, with approximately 17 percent and 13 percent falling into moderate and severe categories.

Blood samples were also collected to measure different NK cell types. NK cells include two main subgroups: CD16+CD56dim cells, which form most of the NK cells in the nervous system that links the central nervous system to the rest of the body (peripheral NK cells). This subtype is cytotoxic, meaning it can destroy cells that enter or harm the body. The second subgroup, CD16+CD56high cells, is less common and contributes to the release of proteins that act as chemical messengers and support immunoregulation. Both groups are considered circulatory NK cells.

How Anxiety and Insomnia Affected NK Cell Levels

Results showed that students who reported anxiety symptoms had both a lower percentage and lower number of circulatory NK cells and their subtypes compared to those without symptoms. The severity of anxiety mattered as well. Students with moderate or severe symptoms showed a notably reduced percentage of circulatory NK cells, while those with minimal or mild symptoms showed only a small and statistically insignificant decrease. Among students with insomnia symptoms, higher anxiety scores were associated with a lower proportion of total peripheral NK cells.

Consequences of Declining Immune Defenses

A drop in NK cells can weaken immune performance, raising the likelihood of various health issues, including infectious diseases, cancers, and mental health conditions such as depression. "Understanding how these psychological stressors influence the distribution and activity of immune cells, especially peripheral NK cells, may provide valuable insights into the mechanisms underlying inflammation and tumorigenesis," Alhamawi explained.

The researchers noted some limitations. Only young female participants were included, a group in which anxiety and sleep problems have been increasing at a disproportionate rate. This narrow focus limits how widely the results can be applied. The team emphasized that studies involving a wider range of ages, sexes, and geographic regions are needed for a more complete understanding of how anxiety and insomnia influence NK cell levels and function.

Lifestyle Measures and the Impact of Stress on Immunity

Previous research suggests that healthy habits, including consistent physical activity, lowered stress levels, and a balanced diet, may help improve NK cell levels and performance. Even so, anxiety and insomnia can interfere with normal biological processes throughout the body, including immune responses, and may contribute to chronic and inflammatory diseases. "Such impacts ultimately compromise overall health and quality of life," concluded Alhamawi.