Feeling Blue and Sleepless May Lower Natural Killer Cell Numbers

Many people are familiar with anxiety, whether it shows up as jittery nerves, a pounding heartbeat, or difficulty sleeping. But for those with generalized anxiety disorder, these feelings can linger and disrupt daily life. When anxiety and insomnia are both present, the effects can extend beyond mental well-being and influence physical health as well.

This motivated Renad Alhamawi, an immunologist at Taibah University, to explore how anxiety and insomnia might interact with the immune system. She and her colleagues focused specifically on natural killer (NK) cells, which circulate in the body and serve as one of the first lines of immune defense.

In a recent study, published in Frontiers in Immunology, the researchers found female students who experienced symptoms of anxiety and insomnia had lower counts of NK cells compared to symptom-free students.¹ These findings suggest that anxiety and sleeping disorders may disrupt the immune system and consequently contribute to the development of other health issues.

The researchers recruited 60 female students between the ages of 17 and 23. The team examined the students’ self-reported questionnaires, which included levels of anxiety and sleep patterns.

Then, the researchers assessed the participants’ peripheral blood samples using surface cell markers CD3, CD16, and CD56 to identify circulating NK cells and their subpopulations. Some of these NK cells exhibit cytotoxicity, while others are involved in cytokine production and immunoregulation.

They found that students with anxiety symptoms had a lower percentage and number of circulatory NK cells and their subpopulations compared to symptom-free students. This observation became more pronounced in those with moderate and severe levels of anxiety. Similarly, students with insomnia had lower proportions and counts of total NK cells.

These findings suggest that anxiety and insomnia have a negative association with NK cells, which may impair the function of the immune system. While the researchers acknowledged the study’s limitations, having only included a small group of young female students, they hope to further explore different age groups, sexes, and more diverse populations from other regions.

“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 in a press release.