Anxiety and insomnia linked to sharp drops in key immune cells

Natural killer cells act as the immune system’s rapid-response team, but the stress of anxiety and insomnia may be quietly thinning their ranks. A study of young women in Saudi Arabia found that both conditions were linked to significantly fewer NK cells—especially the circulating types responsible for destroying infected or abnormal cells. As anxiety severity increased, NK cell levels dropped even further, suggesting a stress-driven weakening of immune defenses.