Why anxiety and insomnia may be quietly weakening young women’s immunity

Anxiety and insomnia may be linked to a drop in key immune cells, leaving the body less equipped to fight disease, according to a study conducted among young women.

Researchers at Taibah University in Saudi Arabia found that symptoms of anxiety or insomnia were associated with fewer natural killer (NK) cells — a type of immune cell that targets pathogens and infected or abnormal cells.

The study, published in Frontiers in Immunology, examined 60 female university students. Participants completed standard questionnaires to assess anxiety and sleep problems, and their blood samples were analysed to measure NK cell levels.

The findings showed that students reporting insomnia had a lower total number of natural killer cells. Those experiencing anxiety symptoms had fewer NK cells circulating in their bloodstream. The effect was strongest among participants with moderate to severe anxiety.

Researchers reported that 75 per cent of the participants showed symptoms of generalised anxiety disorder at varying levels, while more than half reported insomnia. Students with higher anxiety scores consistently showed reduced NK cell counts, particularly when anxiety and insomnia occurred together.

A reduced number of natural killer cells can weaken immune defences and may increase vulnerability to infections, cancer and certain mental health conditions, including depression, the researchers said.

The team said the results offer insight into how mental health and sleep disorders may have direct physiological effects, and could help inform strategies to prevent immune-related illnesses and cancers.