SittingDuckPolicy.com has written up an article on levels of awareness and your readiness to defend yourself.
Lieutenant Colonel John Dean "Jeff" Cooper (May 10, 1920 – September 25, 2006) of the U.S. Marine Corps felt that the most important means of surviving a lethal confrontation isn’t a weapon or fighting skills; the primary tool is the combat mindset.
Safety is something that happens between your ears, not something you hold in your hands.
One chapter in his book, Principles of Personal Defense, Cooper talks about awareness and presents an adaptation of the Marine Corps system to differentiate states of readiness.
This color code has nothing to do with military tactical situations or alertness levels, rather it was all about one’s state of mind. (Based loosely on Wikipedia and the Cooper Color Code.)
Condition White: Unaware and unprepared
If attacked or threatened in Condition White, the only thing that may save you is the ineptitude of your attacker – or sheer luck. When confronted by this type of threat your reaction will probably be “Oh no! This can’t be happening to me!”
Condition White is also known as “head in the clouds,” and means you’re generally unaware of what’s going on in your immediate surroundings. This is the worst condition to be in, and the condition that most would-be attackers hope to find their victims in. The element of surprise is on their side in this condition – not yours.
Some have said that the only time you should be in Condition White is when you’re asleep.
Condition Yellow: Relaxed alert
In Condition Yellow there is no specific threat situation. You use your eyes and ears, and every sense available to you to be aware of your surroundings. You are “taking in” surrounding information in a relaxed but alert manner, like a continuous 360 degree radar sweep.
Read the rest of the article
The rest of the article is available at http://sittingduckpolicy.com/index.php/2009/04/28/what-color-are-you-the-cooper-color-code/ and goes into Conditions Orange and Red.