A new study shows just how strong a pain reliever meditation can be. It also found clues to why meditation can be so effective.

The researchers found that meditation was able to relieve pain better than morphine generally does.

The significance of this study may lie in the fact that so little training was needed to give such strong pain relief.

Pain in this case was based on people's responses to brief heating of a portion of their right leg to 120 degrees Fahrenheit. Meditation caused a 40% lowering of pain intensity and a 57% lowering of pain unpleasantness. Typically, morphine or other pain relieving drugs only lower these symptoms by about 25%.

Fifteen healthy volunteers who had never meditated before were taught a form of meditation known as focused attention. In focused attention, people are taught to concentrate on their breathing and to let go of distracting thoughts and emotions. The volunteers learned this technique by attending four 20-minute classes. Afterwards, when their skin was heated, every volunteer experienced less pain while meditating. Individual values dropped anywhere from 11-93%, compared to the pain experienced in a non-meditating state.

One of the reasons that meditation was so successful in blocking pain may have been that it altered activity in four different regions of the brain. Using a brain scan called arterial spin labeling magnetic resonance (ASL MRI), the researchers measured activity in various regions of the brain while the volunteers' skin was heated.

They found that meditation lowered activity in the primary somatosensory cortex, an area known to be involved in identifying where pain is felt and how intense it is. Before meditation training, activity in this area was very high. After training, when participants were meditating, no activity was detected.

The scans also showed increased activity while meditating in three other brain regions: the anterior cingulate cortex, anterior insula and orbito-frontal cortex. The more these areas were activated, the more pain reduction there was in the volunteers.

The researchers, from Wake Forest Baptist Medical Center, used ASL MRI because it's better at showing longer term brain processes than a conventional MRI scan is.

The significance of this study may lie in the fact that so little training was needed to give such strong pain relief. Less than an hour and a half of training was required. And there are plenty of people who could benefit from a drug-free way to lower pain.

The study appears in the April 6, 2011 issue of the journal Neuroscience.