In Brief

The mystery of muscle relaxation

Muscle relaxation, sometimes enhanced by biofeedback, is often used in the treatment of anxiety and insomnia on the assumption that patients can calm their minds by learning how to relax their bodies. A 2007 article challenges this assumption and raises questions about how this therapy actually works.

The standard theory is that muscle relaxation relieves anxiety by bringing about a physical state that opposes the emergency fight-or-flight response. When muscles are relaxed, heart rate, blood pressure, and stress hormone levels are lowered, and changes in emotions and thinking follow.