Natural killer (NK) cells are part of your immune system’s rapid-response crew—the ones that react quickly when something’s “off,” like infected or abnormal cells. A new study looked at whether two very modern problems—anxiety and insomnia—might be linked to changes in those immune defenders.
Researchers studied 60 female students (ages 17–23) who completed questionnaires about anxiety and sleep symptoms and also gave blood samples so the team could measure different NK cell subtypes.
What they found was striking (and a little unsettling): students reporting insomnia symptoms showed lower overall NK cell counts, and students reporting anxiety symptoms showed lower circulating NK cell levels, with the biggest drops showing up in those reporting moderate-to-severe anxiety.
Important context: this doesn’t prove that anxiety or insomnia caused the immune changes. It’s a focused sample (young women, one region), and it captures a snapshot in time. Still, the results fit a broader pattern many people recognize in real life: when stress is high, and sleep is off, the body can start acting “run down” in ways that aren’t always obvious until you catch something.
The practical takeaway isn’t panic—it’s awareness. If you’re trying to feel steadier this season, think of sleep and stress support as more than a mood issue. This study suggests they may be part of your basic resilience toolkit.
