http://masteringeft.com/masteringblog/about-meditation/meditation-articles/2247-2/

This is on Patricia Carrington’s website and she is the only expert person who has drawn attention to this aspect of meditation…A few years ago I read an article by the Welsh poet Gwyneth Lewis who went to a long 2 day meditation course in a convent.She became distressed but was persuaded to stay.
She became severely depressed not long after that…. the nuns didn’t know it could be bad.
Basically, clichedly I say to myself:
Don’t do too much of anything except being kind to yourself and then to others if possible

http://thoughtbrick.com/meditation/dangers-meditation-10-things-look/
Very few books or articles on meditation mention that it has risks… and now it’s being pushed as the answer to all our health problems.
In the past meditation was within a religious tradition so that you had a priest or a rabbi to turn to.Now the religious aspect is stripped away and it is taught as a method of relaxation without any connection to a community of knowledge and experience.The Church has many flaws but it does have many advantages too.. and ..similarly for religions other than Christian.
If you meditate for too long in one session it can bring up material from your Unconscious.This may be dangerous for depressives and other folk with afflictions more dangerous
Patricia Carrington’s Freedom in Meditation has a chapter on this.
And it is not meant to be a retreat from life…
For some people any form of relaxation is a problem…
sometimes taking walks is a better idea.I know one person who found having massage emotionally distressing… yes,she was anxious but she didn’t feel able to deal with it.
Listening to music is good.Sitting by a tree is good

Some men have gathered followers to their meditation readings and methods and then I read about how awful these men were to their own families… cruel even…We have rushed into spiritual  techniques without the protection of a larger community to hold us and guide us.