Anxiety May Be Quietly Draining Young Women’s Immune Defenses, Study Shows

A new study of a group of young women found that three-quarters showed signs of anxiety. But the research reveals something these students likely don’t know: their anxiety may be quietly suppressing their immune defenses. Scientists examining blood samples discovered significant reductions in natural killer cells—specialized immune cells involved in fighting tumors and infections—with the worst anxiety symptoms linked to up to three-quarters fewer protective cells.

The study by researchers at Taibah University, which examined 60 female students under age 25, found that the more severe the anxiety, the fewer defenders remained in their bloodstream. The findings, published in Frontiers in Immunology, point to a physiological price tag on the mental health crisis affecting young women.

When anxiety paired with insomnia, which afflicted more than half the students, the immune suppression grew even more pronounced. Among sleep-deprived students, every increase in anxiety severity directly predicted fewer natural killer cells, immune cells that destroy infected and cancerous cells.

“These findings suggest that anxiety and sleep disturbances may compromise immune function and contribute to immune dysregulation,” wrote researchers at Taibah University in Saudi Arabia.

The Body’s First Line of Defense

Natural killer cells work as the immune system’s first responders. Unlike other immune cells that need training to recognize threats, NK cells instinctively identify and destroy abnormal cells, such as tumor cells, virus-infected cells, and other cellular troublemakers. They make up about 5% to 15% of lymphocytes circulating in blood, constantly surveilling for problems.

Two main types exist. CD16+CD56dim cells, which constitute the majority, directly attack and kill abnormal cells. CD16+CD56high cells, though less common, coordinate immune responses by releasing signaling molecules. Both populations dropped in anxious students.

NK cells play a critical role in early immune surveillance. Research has linked reduced NK cell levels to poorer outcomes in cancer patients, though this study did not assess cancer risk. The paper cites studies showing NK cell deficiency correlating with worse prognosis in patients with colorectal cancer, liver cancer, and gastric cancer.

How the Study Measured Immune Changes

Researchers recruited healthy female students at Taibah University in February 2025. Participants ranged from age 17 to 23. Nearly all were single, and about half reported no regular exercise.

Each student completed two questionnaires. The GAD-7 assessment measured anxiety symptoms over the previous two weeks. Scores from 0 to 4 indicated minimal anxiety, 5 to 9 mild, 10 to 14 moderate, and 15 to 21 severe. The Sleep Condition Indicator evaluated insomnia symptoms, with students scoring 16 or below meeting criteria for probable insomnia.

Blood samples went through two types of analysis. Standard complete blood counts measured overall immune cell populations. Researchers also used flow cytometry, a lab technique that identifies specific cell types by tagging them with fluorescent markers, allowing precise counts of NK cells and their subsets.

Seventy-five percent of students reported anxiety symptoms at some level. Among these, 45% had mild symptoms, 16.7% moderate, and 13.3% severe. More than half the students (53.3%) reported insomnia symptoms.

Severe Anxiety Linked to Substantially Lower Protective Immune Cells

When researchers compared immune profiles, stark differences emerged. Students with severe anxiety had an average of just 10.9% of their lymphocytes classified as NK cells, compared to 37.5% in students without anxiety symptoms, a 71% reduction based on the study’s data.

The CD16+CD56dim subset, which directly kills abnormal cells, dropped from 29% in students with minimal anxiety to 7.5% in those with severe anxiety, a calculated 74% decline. The CD16+CD56high population fell from 8.5% to 3.5%.

Absolute cell counts followed the same pattern. Students with minimal anxiety averaged 978 NK cells per microliter of blood, while those with severe anxiety had just 285, representing a 71% reduction in the study’s data.

Among students reporting insomnia, statistical analysis revealed moderate negative correlations between anxiety scores and NK cell populations. Students with both conditions faced a double hit.

The study’s regression analysis quantified the relationship: anxiety scores explained 22% of the variation in total NK cell frequency among students with insomnia. The paper reports that each one-point increase in anxiety score corresponded to a 1.565 percentage point drop in NK cells (rounded to 1.6 in lay terms).

Other immune populations—total lymphocytes, monocytes, neutrophils—showed no significant differences between anxious and non-anxious students. Red blood cell counts and platelet levels remained normal across groups.

Why Stress May Suppress Immune Function

Scientists suspect the mechanism involves cortisol, a steroid hormone released during stress, though this study did not measure hormone levels. Previous research has documented elevated cortisol in anxious individuals. The hormone binds to receptors throughout the body, including on immune cells, and activates genes that suppress immune function.

Earlier studies show long-term cortisol exposure reduces various immune cell counts and impairs their function. In cancer patients, anxiety-associated cortisol elevation correlates with reduced NK cell activity and increased inflammatory molecules tied to poor prognosis and treatment resistance.

The connection extends beyond anxiety. Patients hospitalized with depression show decreased NK cell activity compared to healthy controls. Those with major depressive disorder have significantly lower peripheral NK cell percentages. Chronic tinnitus patients experience negative correlations between stress levels and specific NK cell subsets.

Sleep deprivation compounds the problem. Studies link insomnia to increased risk of cardiovascular disease, cancer, and neurological disorders. Poor sleep elevates inflammatory markers and disrupts normal immune cell production and function.

Rising Mental Health Crisis Among Young Women

Mental health conditions have surged among young adults in recent years, with women bearing the brunt. Earlier research in Saudi Arabia has documented high rates of anxiety among female students, with some studies finding more than two-thirds affected. A national screening study in the region showed significantly increased anxiety prevalence, particularly among women.

Studies suggest insomnia affects a substantial portion of the Saudi population, with women, students, and unemployed individuals at highest risk. A systematic review of university students in Saudi Arabia reported rising insomnia rates, especially among medical students and female students.

The pattern extends globally. Women are approximately twice as likely as men to develop anxiety disorders. Young adults report higher anxiety severity than older populations.

What Scientists Still Need to Learn

These findings raise questions about whether managing anxiety or insomnia could help restore immune balance. Do the reduced cell counts translate to higher infection rates or other health problems in anxious young women? How long does immune suppression persist?

Future studies should measure cortisol levels alongside immune cell counts to confirm the proposed mechanism. Functional assays testing whether NK cells from anxious students actually kill target cells less effectively would demonstrate real-world immune compromise. Longitudinal studies following students over months or years could reveal whether immune effects accumulate, stabilize, or reverse with treatment.

Broader populations need examination. The current study included only young women at a single university. Research should expand to men, different age groups, and diverse geographic regions.

If the connection holds up across larger studies, these findings suggest that addressing mental health in young adults may carry benefits beyond psychological well-being. The research adds to mounting evidence that psychological and physical health cannot be separated. Anxiety and insomnia might make people feel physically worse, but they also may be changing bodies in ways that persist.