In this study below, it was found that meditation, or more specifically transcendental meditation, can lower blood pressure.

Combined with other practices, including breathwork and guided relaxation, which are also shown to lower blood pressure, we believe there is a strong basis for maintaining healthy cardiac and blood pressure using meditation and relaxation techniques.  We recommend and use these techniques in our programs to help augment your health, not as a substitute for proper medical attention and care.

University of Kentucky (2008, March 15). Meditation Can Lower Blood Pressure, Study Shows. ScienceDaily.
http://www.sciencedaily.com­/releases/2008/03/080314130430.htm