The World Health Organisation estimates that high blood pressure leads to over 7 million deaths each year, about 13% of the total deaths worldwide. If people lower their blood pressure, they are less likely to die or to have heart attacks and strokes. If someone’s blood pressure is only slightly too high, they may prefer trying to lower it by changing their lifestyle rather than starting on drugs. Although we know that relaxing can counteract the short-term increases in blood pressure that are caused by stress, we don’t know if a sustained programme of relaxation can produce long-term reductions in blood pressure or decrease the risk of death, heart attack and stroke.
Our review pooled findings from 1,198 people with blood pressure over 140/85 mmHg who were enrolled in 25 randomised controlled trials. These trials compared the effect of relaxation either with no treatment or with a dummy treatment which wasn’t expected to reduce blood pressure. Overall, relaxation reduced blood pressure by a small amount: the average reduction was 5/3 mmHg, but might be anywhere between 8/5 mmHg and 3/2 mmHg. Different trials gave different − sometimes inconsistent − results. Many of the trials were not well designed or conducted. In the good quality trials, relaxation resulted in smaller average reductions in blood pressure and the results could even be consistent with an average increase in blood pressure. Even when all the trials were put together, the combined group of all the people in all the trials wasn’t large enough and the trials didn’t run for long enough to tell us whether relaxation could reduce the risk of death, heart attack or stroke. Few people reported side-effects of relaxation and, on average, people were just as likely to report side-effects of the comparison treatment.
Different types of relaxation were taught in different trials. It was difficult to disentangle their effects, especially as many trials used a combination of methods. Overall, we found no evidence that autogenic training was effective. Progressive muscle relaxation, cognitive/behavioural therapies and biofeedback seemed to be more likely to reduce blood pressure. However, some of the reduction in blood pressure was almost certainly due to aspects of treatment that were not related to relaxation, such as frequent contact with professionals who were trying to help. —Cochrane 2009