It is a very efficient technique for achieving a deep state of relaxation quickly. It can be a potent technique for halting the momentum of a panic reaction when the first signs of anxiety come on.
It is also useful in reducing symptoms of hyperventilation or over-breathing, which can cause light headed-ness and further panic. Practice regularly for at least 5 minutes per day to reduce stress, anxiety and panic.
4. When you have exhaled completely, return to normal breathing for two breaths.
5. Then repeat the steps above for at least 5 minutes. This should involve at least 10 cycles. If you start to feel light headed, stop for 30 seconds, or breathe a few extra normal breaths, then start again. Try this exercise whenever you feel anxious and see the calmness it brings.
Reference: Bourne, E. (2005), The Anxiety & Phobia Workbook, New Harbinger Publications, USA