Ever learning, and never able to come to the knowledge of the truth. 2 Timothy 3:7
"What contemporary and ancient meditators have always
known, ....the practice
is not all peace, love, and blissful glimpses of 
unreality. Sitting zazen, gazing at their third eye, a person can encounter extremely unpleasant emotions and physical or mental disturbances.
Zen Buddhism has a word for the warped perceptions that can arise during meditation: makyo, which combines the Japanese words for “devil” and “objective world.” Philip Kapleau, the late American Zen master, once described confronting makyo as “a dredging and cleansing 
process that releases stressful experiences in deep layers of the mind.”
However, this demanding and sometimes intensely
distressing side of meditation is rarely mentioned in scientific
literature, says Jared Lindahl, a visiting professor of religious
studies at Brown University, who has an interest in neuroscience and
Buddhism.
Along with Willoughby Britton, a psychologist, the two meditators have co-authored a
study that documents and creates a taxonomy for the variant
phenomenology of meditation. The paper, published in Plos One, is the beginning of an ongoing series of studies.
The researchers identified 59 kinds of unexpected or unwanted
experiences,
which they classified into seven domains:
cognitive,
perceptual,
affective (related to moods),
somatic,
conative (related to
motivation),
sense of self,
and social.
Among the experiences described
to them were feelings of
anxiety and fear,
involuntary twitching,
insomnia,
a sense of complete detachment from one’s emotions,
hypersensitivity to light or sound,
distortion in time and space,
nausea,
hallucinations,
irritability,
and the re-experiencing of past
traumas.
The associated levels of distress and impairment ranged from
“mild and transient to severe and lasting,” according to the study.
Most would not imagine that these side-effects could be hiding behind
the lotus-print curtains of your local meditation center."
LilaMacLellan