What's the difference between anxiety, stress, and nervousness? originally appeared on Quora, the place to gain and share knowledge, empowering people to learn from others and better understand the world. You can follow Quora on Twitter, Facebook, and Google Plus.

First and foremost, anxiety is a disorder. It’s a condition that can be diagnosed, based on a collection of symptoms like the ones listed below (From WebMD). It’s ongoing. Stress and nervousness are not diagnosed and tend to be more short-lived. The definition of stress only adds to the confusion here because half the world considers stress to be what happens to you like traffic jams, arguments and deadlines and the other half thinks of it as how you feel inside when you encounter things like this.

Nervousness is something you feel temporarily, like before a job interview, or getting up to give a speech or trying something new like skiing for the first time. Nervousness usually goes away after a while, stress comes and goes almost randomly in response to various experiences, and anxiety is something you feel on an ongoing basis (not necessarily in response to any particular experience).

I heard Frank Sinatra say to Larry King that he got nervous every time he walked out on stage, but he said that nervousness would always go away within a few minutes. Carly Simon famously quit doing live concerts and Carol King had to get help with her anxiety before she could return to the stage. So, just to be crystal clear: Frank suffered from nervousness and Carly and Carol had anxiety. For all three performers, the idea of getting up in front of thousands of people is going to be stressful.

Having pointed out the differences between anxiety, nervousness and stress, it may surprise you that these three different conditions are all created in the exact same place in the body. It happens when the Hypothalamic, Pituitary, Adrenal (HPA) axis is activated that you feel anxious, nervous or stressed.

With anxiety, it’s probably fair to say that you have a malfunctioning HPA axis (it’s switched on much or all of the time) With stress, if the HPA axis is switched on when you hear a loud crash in the middle of the night, that’s good! You want to be on high alert in case there is an intruder in the house. There’s more of a direct cause and effect relationship when we are talking about what causes our stress symptoms. If the HPA axis is switched on when you are first learning to drive, or to ski or to rock-climb that’s good too. Your nervousness causes you to be extra careful in these situations.

So here we see that nervousness comes on when we try something new or challenging but goes away when we get accustomed to it, stress comes and goes as challenges arise in our lives (almost randomly) and anxiety, tends to stick around and is a condition that needs to be treated.

Stanford Professor, Dr. Robert Sapolsky, who wrote the book: Why Zebras don’t Get Ulcers, likes to say that Zebras don’t get ulcers (a condition that can be caused by chronic stress) because they don’t think about the lion when the lion’s not there. We human beings (with our large imaginative brains) can and DO think about the lion when the lion is not there. (Your lion could be anything you worry about excessively.) If you have an anxiety disorder you are very likely to worry about all sorts of things that pose no real danger.

What Are the Symptoms of Anxiety Disorders? (From Web MD)

It depends on the type of anxiety disorder, but general symptoms include:

• Feelings of panic, fear, and uneasiness

• Problems sleeping

• Cold or sweaty hands or feet

• Shortness of breath

• Heart palpitations

• Not being able to be still and calm

• Dry mouth

• Numbness or tingling in the hands or feet

• Nausea

• Muscle tension

• Dizziness

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