A 2003 study published in Psychosomatic Medicine examined the effects of an 8-week mindfulness meditation program on brain activity and immune function. After the intervention, participants showed increased electrical activity in the left prefrontal cortex, a pattern associated with positive affect and approach-oriented emotions.
The researchers then gave all participants a flu vaccine and measured antibody production. The meditation group produced significantly more antibodies than the control group. More interesting, the magnitude of brain change predicted the magnitude of immune response. The greater the left-sided brain shift, the stronger the immune response.
This study demonstrated that the brain and immune system do not operate independently. Meditation appears to influence both simultaneously, through mechanisms that are still being studied. The practical takeaway is that a contemplative practice may have protective health effects beyond stress reduction.
Source: Yoga Research: Brain Structure & Function on ashtanga.tech. Original research.