Can too much stress in your life cause sickness? This was once thought to be a wellness cliché, but a growing body of research suggests that there may be real truth behind this theory. Chronic stress not only affects how you feel on an emotional level, but it also alters immune function on a cellular level. Ultimately, that changes how well the body defends itself against foreign invaders, such as bacteria, viruses, pollutants, and other germs. 

A recent study published in Frontiers in Immunology found that insomnia and anxiety were linked to significantly lower levels of natural killer (NK) cells. These cells are among the immune system’s first line of defense. Findings indicated that the more severe the anxiety, the steeper the decline in NK cells. That means that stress and anxiety may actively thin your immune system’s army, in a way, making you more susceptible to illness. 

What Are NK Cells And What Do They Do?

NK cells belong to the innate immune system, which you can think of as the body’s rapid-response team. These cells monitor blood and tissues, identifying and destroying damaged, infected, or abnormal cells before problems arise. There are two subtypes of NK cells:

• CD16+CD56dim cells: These cells make up the majority of NK cells and are very cytotoxic, which means that they directly destroy harmful cells. 
• CD16+CD56high cells: These cells assist with regulating immune signaling and inflammation. 
• If NK cell numbers decline too much, the immune system may find it difficult to both contain infections and abnormal cell growth in the early stages. That ultimately raises long-term health risks. 

What Did The Study Reveal?

To begin, researchers examined 60 female university students aged 17 to 23. Participants completely validated questionnaires, assessing self-reported anxiety and symptoms of insomnia. They also provided blood samples in order for researchers to measure different NK cell populations. 

Researchers noted that mental health responses were very bleak, with 75% of participants reporting anxiety symptoms. Roughly 17% and 13% of participants fell into moderate and severe categories. Additionally, 53% of the participants experienced sleep difficulties that researchers found consistent with insomnia. Besides these startling findings, researchers noted that blood samples revealed a much clearer picture:

• The severity of anxiety mattered, with mild anxiety showing minimal, non-significant changes. Moderate to severe anxiety was associated with a notable reduction of NK cells. 
• Students who reported anxiety symptoms exhibited both lower numbers and lower percentages of NK cells, including cytotoxic types. 
• In students who reported sleep disturbances, higher anxiety scores revealed an even greater decline in total peripheral NK cells. 

An Important Note

The study focused on young women between the ages of 17 and 23. Sleep disorders and anxiety are rising the fastest in this age group. Although that makes the findings relevant, it also limits how broadly they can be applied. Researchers need future studies across different ages, sexes, and regions in order to fully understand how stress affects immune function. 

The Takeaway

Stress is not just something that lives in the mind. The constant edge that you cannot shake or racing thoughts may reshape the immune system and how it functions, leaving your body more vulnerable to illness. This study serves to remind people that having stress management practices can help your emotional, mental, and physical wellbeing. Allow your whole body to flourish in the immediate and long-term when you get your stress under control.

Vincent Stevens

Vincent Stevens is the senior content writer at Dherbs. As a fitness and health and wellness enthusiast, he enjoys covering a variety of topics, including the latest health, fitness, beauty, and lifestyle trends. His goal is to inform people of different ways they can improve their overall health, which aligns with Dherbs’ core values. He received his bachelor’s degree in creative writing from the University of Redlands, graduating summa cum laude. He lives in Los Angeles, CA.