This is an intense kriya for the neck and thyroid gland in particular. There are studies that show a direct impact of pranayama and asana on regulating the thyroid gland, responsible for many things in our body like metabolism and overall health. See your homeopath or doctor about getting a blood test if you have symptoms of hyper or hypothyroidism (ask for a full panel of bloodwork, not just the general public one - two or three tests). If you notice a change in diet (either super high metabolism) unexplained weight loss or weight gain, hair loss, dry skin, irritability, anxiety, depression. Of course these can account for many things - but the thyroid is something to get checked. Female body's are prone to hypothyroidism.

In good health!