Nyasa can mean…
Consecration of parts of the body
To arouse consciousness in…
Imbuing with mantras.
It is a very old practice in Tantra. A variation of it has been used in modern times in Rotation of Consciousness practices, which I will describe below.
It can also be used in Maithuna foreplay.
Essentially the practice involves infusing divinity or divine energy into ones body or into the body of another.
There are different variations of Nyasa. For example the conscious placing of the 50 letters of Sanskrit alphabet onto parts of ones body ( known as Matrika Nyasa)…Matrika is the word for the Sanskrit alphabet. Mother.
Another form is called Sadanga Nyasa…Sad means Six, Anga means Limbs…it involves mentally or physically placing mantra into six parts of the body. Some say heart, forehead, crown, both eyes, both hands palms and back. Others say feet, knees, genitals, heart, forehead, crown.
Nyasa can be done externally using the tips of the fingers of the right hand to touch the parts of the body, or it can be done internally, visualising.
There are generally complicated mantras ascribed to Nyasa but one can use instead the universal mantra Om as advised to be done constantly by wandering sages in the Aruni Upanishad…
Uttering “Om” “Om” “Om”, they should mentally place this Mantra, the Upanishad, in the different parts of their body
Aruni Upanishad ~ http://www.advaita.it/library/aruni.htm (4th BCE)
Or one could use whatever variation of Om they prefer, such as Amen, Amin, or some other charged word like Love or Peace.
Nyasa is a very important and powerful Tantric rite. It is placing of the tips of the fingers of the right hand on various parts of the body, accompanied by Mantra. ~ Sw Sivananda Saraswati
”Placing his hand on his heart he says the So Hang (So – Ham) mantra, ( I am That (He/She)) thereby identifying himself with the Devi” ~ Arthur Avalon Translation of the Maha Nirvana Tantra
A complicated Nyasa practice is described at http://www.shivashakti.com/shodha.htm
But in these times of shorter lifespans than in the Vedas, these times of a lack of servants, devotees and wives (ahem !) to tend to our needs so that every waking moment is available for doing complicated rituals, I don’t think it is disrespectful to use the simpler idea described in the Aruni Upanishad. One possible practice follows…
Lie down. Either on mat, or do practice in bed before sleep. Or sit.
Close eyes and release tightness in body. Settle mind.
Visualising the form of the mantra (OM), or instead some symbolic representation of charge, or energetic force that appeals to you, (light, warmth, etc) as you move your awareness in a systematic rotation through the parts of the body be aware of that charge briefly and fully infusing the part of the body you dwell on.
Right hand thumb, first finger on right hand, second finger, third finger, small finger, palm of hand, back of hand, wrist, lower arm, elbow, upper arm, shoulder, arm-pit, right side of body, waist, right hip…..
Be fully aware of the placing of the mantra…
Right thigh, knee, back of knee, calf muscle, shin bone, ankle, heel, sole of foot, top of foot, right big toe, second toe, third toe, fourth toe, fifth toe.
Move your awareness with the mantra to…
The left hand thumb, first finger on left hand, second finger, third finger, small finger, palm of hand, back of hand, wrist, lower arm, elbow, upper arm, shoulder, arm-pit, left side of body, waist, hip, left thigh, left knee, back of knee, calf muscle, shin bone, ankle, heel, sole of left foot, top of foot, left big toe, second toe, third toe, fourth toe, fifth toe.
Keep your awareness moving smoothly and at a pace that holds your attention. Quite quickly is fine. Slower if suits….
The whole of right leg, the whole of left leg, right buttock, left buttock, tail bone, small of back, middle of back, upper back, right shoulder blade, left shoulder blade, the whole back…
Back of neck, back of head, top of head, right side of head including the right ear, left side of head including the left ear, forehead…
right eye, left eye, eyebrow centre, tip of nose, right nostril, left nostril, right cheek, left cheek, upper lip, lower lip, teeth, tongue, chin, throat, right side of chest, left side of chest, centre of chest, ribcage….
upper abdomen, navel, lower abdomen, the whole belly, the groin, the whole front of body, the whole back of body, the whole front of body, the whole back of body, the whole body together, the whole body together, the whole body together…..
After completing round of Nyasa, you can either repeat more rounds, or ground into your surroundings and open your eyes, or go to sleep, if you have not already fallen asleep…
OM TAT SAT