Everyone doing the Sandhyavandanam would have certainly come across Pranayamam. The pranayamam is done while mentally reciting the mantra- ”
Om Tat Savithur Varenyam Bargo Devasya dhimahi dhiyo yonaha prachodayath
Om Apojyothi rasomrutham brahma bhoorbuvasuvarom”.
6 lokas(worlds) are known to be above Bhoo lok(Earth). They are namely, bhuvar lokam, suvar lokam, mahar lokam, jana lokam, tapa lokam & the satya lokam. While reciting the 1st part, i.e “Om bhoo; Om bhuvaha…….”, the life force(prana) travels from foot to the head in the manner of travelling through these 7 worlds. Having reached the satya lokam, the next part begins.
“Om tat savitur varenyam……..” being the 2nd part refers to the core of the Gayatri mantra. It means, ” I meditate on the holiest shining aspect of the almighty. May it enlighten our thoughts(buddhi)”.
The next part is, “Om apo jyoti rasomrtam…….”. This means, ” Om is water, it is the light, it is the earth which gives the food, it is the air which supports life, and it is the ether which is spread all around .It is also the holy seven worlds”. After this the breath which was held at the start is exhaled.
The breath control involves three parts. They are, the rechakam(exhalation), purakam(inhalation through single nostril) & kumbakam(holding/locking the breath). The pranayamam having an intimate link with the Gayatri mantra is known to have benefits such as arogya vriddhim(improvement of health), balam(strength increase in both physical & mental strength), ayushya vriddhim(extension of life) & so on.