Are these kriyas some sort of self-hypnosis or some sort of New Age phenomenon?
This yoga is at least 1000 years old and is documented in the Kularnava Tantra and in the works of the great Tantric scholar Abhinvagupta and particular forms of kriyas can be found there. Some popular yogis and scholars have doubted the authenticity of this path but none who have done so show any familiarity with the classical literature of this tradition. This approach has gone under many names such as siddha yoga, sahaja yoga, mahayoga or siddha mahayoga. Similar phenomena to kriyas also occur among some Qi Gong students. Spontaneous trembling, shaking, verbal noises, and body movements are common there as well. Nevertheless gatherings of siddha mahayoga practicioners share many of the same characteristics of any other group gathering. Some people will try to fit in by emulating the behavior of those around them. There is no doubt that some people may feel the need to affect kriyas and others will accentuate kriyas that they have. This may not even be conscious behavior. Gurus of th