Anxiety is not a malfunction. The alarm is doing what it was built to do, which is get you ready for something, and the trouble usually starts with how long it stays on rather than with the fact that it switched on.

What the research says

An influential review of what researchers call perseverative cognition argues that worry and rumination keep stress related activation in the body going long after the stressful event has passed, which is how a mental habit turns into a physical load. It is the carrying on, not the initial response, that the review points at. This is a review of an argument and the evidence for it rather than a single trial, so read it as a well supported way of thinking rather than a settled fact.

Strength of evidence: one line of research. A single study, or a theoretical account.