Conclusions Due to exploratory design s and high risk of bias , the effectiveness of hypnosis or hypnotherapy in stress reduction remains still unclear .
Background Although hypnosis and hypnotherapy have become more popular in recent years , the evidence for hypnosis to influence perceived stress is unclear .
In this systematic review we search ed and evaluated r and omized clinical studies investigating the effect of hypnosis on perceived stress reduction and coping .
The impact of self-hypnosis and Johrei on lymphocyte subpopulations at exam time: a controlled study
In a prospect i ve r and omised controlled trial , 48 students were r and omly assigned to stress reduction training before exams with self-hypnosis , Johrei or a mock neurofeedback relaxation control .  Peripheral blood lymphocyte sub population s and self-reported stress ( Perceived Stress Scale ) were measured before training and 1 - 2 months later as exams approached . Absolute number and percentages of CD3(+)CD4(+ ) and CD3(+)CD8(+ ) T lymphocytes , CD3(-)CD56(+ ) Natural Killer cells ( NK cells ) and NK cell cytotoxic activity was measured from venous blood . Stressed participants showed small but significant declines in both CD3(-)CD56(+ ) NK cell percentages and NK cell cytotoxic activity levels while CD3(+)CD4(+ ) T cell percentages increased , changes supported by correlations with perceived stress . The effects of stress were moderated in those who learned Johrei at exam time ; 11/12 showed increases in CD3(-)CD56(+ ) NK cell percentages with decreased percentages of CD3(+)CD4(+ ) T cells , effects not seen in the relaxation control group . Stress was also buffered in those who learned and practised self-hypnosis in whom CD3(-)CD56(+ ) NK cell and CD3(+)CD4(+ ) T cell levels were maintained , and whose CD3(+)CD8(+ ) T cell percentages , shown previously to decline with exams , increased . The results compliment beneficial effects on mood of self-hypnosis and Johrei . The results are in keeping with beneficial influences of self-hypnosis and provide the first evidence of the suggestive value of the Japanese Johrei procedure for stress reduction , which clearly warrants further investigation
Conclusions Due to exploratory design s and high risk of bias , the effectiveness of hypnosis or hypnotherapy in stress reduction remains still unclear .
Background Although hypnosis and hypnotherapy have become more popular in recent years , the evidence for hypnosis to influence perceived stress is unclear .
In this systematic review we search ed and evaluated r and omized clinical studies investigating the effect of hypnosis on perceived stress reduction and coping .