A chemical brain disorder that causes one to worry about everything, even things they don't particularly care about. Also causes one to not be able to relax properly. Most people do not take this disorder seriously, even though it is very serious and can cause a lot of problems in a sufferer's life.

Briefly, "the realization that each random passerby is living a life as vivid and complex as your own." Originally from the Dictionary of Obscure Sorrows, which has a lot more beautiful neologism definitions like this you might enjoy.

A mental illness that involves excessive, exaggerated anxiety and worry about everyday life events. It differs from regular anxiety in the way that little worries are over analyzed to the point of a possible anxiety attack which is very similar to a panic attack.

Some symptoms are:
fatigue
ongoing worry
unrealistic view of problems
headaches
sweating
trembling
difficultly concentrating
being easily startled
insomnia

AKA: GAD