To be frank, your description of your son does not indicate depression. Do you see any sign that he is not mastering the various challenges of home, school and peer life? It is very normal for people to feel sad some of the time. The key variables are the precipitants to the sadness and the degree of proportionality of the sadness. Fears at nighttime are quite prevalent during childhood, and in your son's case it doesn't seem that they are interfering with his sleep pattern. Re: the fears, ask him what might help him to feel better. See what, if anything, he suggests.