Yes and that is why 180 or any should be given at deployment, which they are discontinuing. However, I believe it is very helpful to those managing severe anxiety.
The anxiety is typically caused by the defense mechanisms in the body trying to block the retrieval of an emotionally traumatic memory when something in the current environment is stimulating retrieval.
For example, the tightening of the inter and outer costal muscles in the chest blocks the afferent spinal nerves from transmitting emotional discomfort to the central nervous system. This is one of the reason that stellate ganglion nerve block shots and the placebo stellate ganglion shots both work for PTSD treatment, but only temporarily. I talked with the researchers at Walter Reed about this and was not impressed.
The chest muscle contractions give that compressed chest feeling and make it difficult to breathe during the anxiety attack.