Regular sickness
If you feel like you’re constantly struggling with sniffles or other sickness, stress could be the main factor. Stress may have negative effects on your immune system. Studies reveal that higher stress levels are associated with increased susceptibility to infection.
In one study, 116 older adults were given the flu vaccine. Those with chronic stress had a weakened immune response to the vaccine, showing that stress may be associated with decreased immunity. Similarly, one analysis studying 27 studies revealed that stress was linked to increased susceptibility of developing an upper respiratory infection.
However, stress is just one piece of the puzzle when immune health is involved. A weakened immune system can also be caused by:
- A low-nutrient diet
- Substance use
- Physical inactivity
- Disorders of the immune system, such as AIDS