In Kundalini Yoga kriyas, a vast energy is generated that produces psychic heat which opens the pranic nadis (channels) that may be blocked. When this opening happens, there can sometimes be a quick shift in blood pressure causing dizziness. Jalandhar Bandh regulates this phenomenon.
By applying this lock, the thyroid and parathyroid glands are stimulated which cause them to secrete optimally and activate the higher functions of the pituitary. If the lock is not applied, the breathing exercises can cause uncomfortable pressure in the eyes, ears, and hearing. It is a general rule to apply Jalandhar Bandh in all meditations unless otherwise specified.