Like walls and fences, it is symbolizing the inaccessibility of something. The repetition of this image points to the inability to move forward on the path undertaken. The area you cannot reach because of the barrier is the higher reality you want to achieve. Something is interfering with your path, preventing you from getting what you really want in life.
Gallery of dreams
One of the reasons why people always get involved in road accidents is that, they are tired while driving, or that they lack sleep. Many people do not realize that their performance can be highly affected by having not enough sleep. Sleep deprivation can affect reaction as well as decision making, not to mention that it could make a person unable to drive well. It goes the same with drunk driving.
In most kids, lack of sleep can surely result to ADHD (Attention Deficit Hyperactivity Disorder), which is the opposite with the adults. Children between 7 and 10 who gets less than 8-hours of sleep every night will likely to become inattentive, impulsive and hyperactive. Their sleeping patterns can easily affect their brain.