An anxiety/panic attack is physically scary the very first time, but by the tenth time what you're really afraid of is the loss of control and the anticipation of anxiety. Chronic sleeplessness is often the same way. Dealing with literally sleeping better is one thing, but at some point the real issue becomes the mental concern with sleep itself.
Dealing with physical anxiety symptoms is good, but if you're mentally anxious your first thought after dealing with an anxiety attack by breathing deeply is "okay, but what if it doesn't work the next time?". It's that mental attitude that I think many people have trouble dealing with.