Murccha is special type of Pranayamic exercise where a Yogi locks the chin and then breathes in air at a very slow pace. It is very pleasing and also creates a loss of consciousness and a sense of trance and sublimation.
According to Hatha Yoga, a primitive Yogic book, this sense of being obligated from awareness that is generated due to this Murccha is also believed to bring about some values of spiritualism. For that one needs to follow a rigorous meditation afterwards. There are few sources that inferred that to aggravate this sense of stupor, several drugs are being consumed thereby supplementing this Murccha exercise.
As far as techniques are concerned, one ends deep inhalation and then practices certain techniques of pranayama, like Kumbhaka with Jalandhara. One continues with this condition as long as this sense of the trance is created. To increase this sense of stupor for an elongated period of time, a single round is not enough. Several rounds are required.
If this exercise is continued for quite a few days, it will lead to a mental condition, which amounts to loss of awareness. This mental state , according to Hatha-Yoga , it is not only pleasing and also aids in increasing concentration . This happens just because it excludes all sensory disruptions and allows the mind almost free from all other relating ideas. In addition, as per Gheranda-Samhita record, a special technique of this Pranayama of fixing mind between two eye brows.