Disorientation

Nyams arise via disorientation in terms of  habitual tendencies. As soon as referential perceptual mechanisms are released—to whatever degree—the psychophysical fields of the senses begin to relax into their own condition.

p76, Shock Amazement: The four naljors and four ting-ngé’dzin from the Dzogchen series of the nature of Mind.   Khandro Déchen and Ngakpa Chögyam,  Aro Books Worldwide, 2018, ISBN 978-1-898185-45-1 

Fleeting glimpse

We say ‘only a nyam’ because a nyam is not the nondual state, but one can experience the nondual state momentarily, and the afterglow of that is called a nyam.  This does not detract from there having been a fleeting glimpse of the nondual state.

p87, Emailing the Lamas from Afar, Ngakpa Chögyam and Khandro Déchen, Aro Books, 2009, ISBN 978-0-9653948-5-7  

A natural movement toward non-duality

   The word nyam means meditational experience or meditational manifestation.  When we practice meditative methods of any kind, experiences occur due to the fact that we are not engaged with duality as intensely.  These experiences are valid in as much as they reflect the fact of our engagement in practise.  Nyams are not realisation per se, but they partake of a natural movement toward nonduality.
Nyams—being unstable—have no enduring characteristics.  They are therefore unreliable as indicators of anything beyond the fact that the pattern of dualism has been disrupted. 

p215, Entering the Heart of the Sun and Moon Ngakpa Chögyam and Khandro Déchen,  Aro Books, 2009, ISBN 978-0-9653948-3-3