Sit comfortably in Padmasana with eyes closed.

Close the right nostril with the right thumb and inhale very slowly through the left nostril.

Keeping the right thumb over the right nostril, close the left nostril with the last three fingers of the same hand and retain the breath as long as you can but without any discomfort of breathing.

Releasing the thumb from the right nostril, gently exhale through it as long as you can.

Reverse the cycle by closing the left nostril with last three fingers of right hand and inhaling through the right nostril.

Keeping the last three fingers on the left nostril, close the right nostril with the right thumb and retain the breath as long as you comfortably can.

Release the last three fingers from left nostril, gently exhale through it.

Alternating the cycle is one Pranayama.

Benefits : Physically, the body becomes healthier as deeper breathing dispels residual carbon-dioxide and increases the energy levels. The increased supply of fresh oxygen results in better repair, maintenance, digestion and improves better sleeping. Mentally, regulation of Prana significantly reduces lethargy and restlessness of the mind.  The mind is in better state for meditation and concentration.

Time & repetition : Start with 10 Pranayama cycles and then gradually increase to 20 cycles. You can do this in the morning and evening, but on empty stomach or at least 3 hours break from your last meal.