All forms of meditative practices have been shown to have an effect on the psycho-neuro-hormonal-immune axis in several ways.
Firstly, considering that meditation involves being in a state of “thoughtless awareness”, there is a signature effect as recorded in the electrical activity of the brain or Electro Encephalogram (EEG). During meditative states, EEG coherence between the two hemispheres is seen. EEG coherence is understood as a measure of cortical connectivity. Higher values of coherence have been interpreted as evidence of functional coupling, information exchange or functional coordination between brain regions.
Similarly changes in the endocrine or hormone levels are seen which favor reduction in stress hormones such as cortisol, and catecholamines,release of endorphins and melatonin as an example.
In addition, there are beneficial immune effects seen. These have ranged from adaptive immunity (i.e., antibodies for humoral immunity and cell mediated immunity as measured by T and B lymphocytes) to innate immunity (including natural killer cells or NK cells). These changes have also, been studied in cancer, HIV/AIDS and other groups of patients. Interestingly, in one study of elderly persons, when the specific immune cell response was evaluated, the effects of Tai Chi meditation was comparable to persons given only varicella zoster or shingles vaccine. The effects of meditation and vaccine were additive.
Overall studies have shown that people with various disorders have benefited from mediation, including: epilepsy, premenstrual and menopausal symptoms, major depression, and other non-psychotic mood disorders, multiple sclerosis, asthma, chronic anxiety, opiate dependence, fibromyalgia, rheumatic pain, and sleep disturbances to name a few.