I've had it for free-floating anxiety, which is usually triggered by worrying about what others have said or done, or might say and done, and ruminating far too often about just about everything. It's a bit tricky to explain in brief, but it got especially bad a few years ago where I just felt so angry and helpless and did a great job of bottling it all up.
Anyhoo, it - and hypnotism - was very effective. CBT taught me how to change my thinking, and hypnotism helped block out some awful things I went through in my teens and 20s.