NY Times article Is Buddhism Good for Your Health? (registeration necessary) is a good read.  It talks about the efforts by U of Wisconsin neuroscientists to study effects of meditation scientifically with help from Tibetan Buddhist monks.

The Wisconsin researchers, for example, are focusing on three common forms of Buddhist meditation.

One is focused attention, where they specifically train themselves to focus on a single object for long periods of time.

The second area is where they voluntarily cultivate compassion. It's something they do every day, and they have special exercises where they envision negative events, something that causes anger or irritability, and then transform it and infuse it with an antidote, which is compassion.

The third is called 'open presence.'  It is a state of being acutely aware of whatever thought, emotion or sensation is present, without reacting to it.  They describe it as pure awareness.

I have done all three types of meditations in the past but found some problems in practicing them everyday.

First problem is the lack of compelling need to create the necessary discipline.  Being deeply hurt emotionally and release from the pain is a good enough, but I am no serious wounds like that, just minor half-healed scars.  Lacking why makes it difficult to keep doing it.

Second problem is the detachement from life that results.  For example, I can look at a baby and, with an effort, erase all effects of my vision such as warmth and love.  It's not an easy effort and maintaining the state takes a lot of practice like trying to balance oneself on a razor's edge.  Still, doing it leaves me empty, not happy, like one feels after reading a stack of Existentialism books.

Process is different from desensitization, but the effect is similar.  It's like shattering a vase, erasing the essense of the vase and emptying its content.  I think the voluntary cultivation of compassion is the attempt to glue the vase back.  Maybe the professional monks know better, but I am not sure if the result is as good as new.

Another thing is that mind and body sometimes acts separately.  When my dog died, I felt emotional pain so I shut part of my mind down.  Meditation is great for emergencies.  But I found tears running down my calm stony face.  Cocooned, I felt no sadness but tears ran like river.  Yes, that was a weird experience.

The last problem was the mentioned in the article.

The fact that the brain can learn, adapt and molecularly resculpture itself on the basis of experience and training suggests that meditation may leave a biological residue in the brain — a residue that, with the increasing sophistication of new technology, might be captured and measured.

No kidding.  I believe that every action one takes, everything one sees, hear, smell and touch, every word one utters, and every thought one has changes us in body and mind.  Hit someone in the face once, you change.  Read Koran or Bible, you change.  Look at a flower, you change.  Everything changes us, but meditation can affect one as strongly as trauma or life long abuse can.  Powerful stuff.

I think the research is a Good Thing because people will finally learn the real benefits as well as dangers of meditation.