A study involving 60 young women suggests a link between insomnia or anxiety and a weaker immune system. Researchers from Taibah University found that participants experiencing symptoms of anxiety or insomnia had lower numbers of 'natural killer cells,' which are crucial for fighting pathogens. The study, published in Frontiers in Immunology, analyzed blood samples and questionnaire data, indicating that higher anxiety scores correlated with fewer natural killer cells, particularly in those with moderate to severe symptoms.