When I was first studying psychology, thirty years ago, I learned that about 10-20% of children are born with a temperament that is highly reactive to anything new and unfamiliar. Some of these children go on in life to be anxious, timid or shy (or, as we shy people like to say, "slow to warm up.") A much smaller number of children, about 1-5% were diagnosed at that time with a full-fledged anxiety disorder.
Nowadays, there are still 10-20% with that reactive temperament, but the number of children with a diagnosable anxiety disorder has skyrocketed, up to 25% according to the National institute of Mental Health. A report from the National Institutes of Health adds, "There is persuasive evidence from a range of studies that anxiety disorders are the most frequent mental disorders in children and adolescents...." These new numbers must be viewed skeptically, of course, because of the trend towards looser and broader definitions of mental illness. Many commentators have linked this trend to the influence of pharmaceutical companies on diagnosis and prescription patterns.
Despite these caveats, however, I believe that childhood anxiety is indeed on the rise at every level, from fears of monsters under the bed to phobias and panic attacks to severe anxiety disorders.
Last year I gave a lecture on childhood anxiety to parents at a public elementary school. I heard about children who couldn't be in a different room from their parents, even to use the bathroom, children who were too afraid of the water to swim or even take a shower, and children who were too afraid of making a mistake to function well in the classroom.
In my practice I have seen more and more children who have too much social anxiety to go to school, too much stress about grades to enjoy life, and too much separation anxiety to achieve independence as they grow older. My colleagues report the same rise in fears, worries, and anxieties.