I have done that a few times during sleep because I found the dream so interesting. Also, however, it can mean that you are focusing on one thing and can't get something off of your mind, so it's kind of hard to really concentrate on anything else anyway.

It can also signify an obsessive compulsion, or simply a abnormal amount of serotonin to the brain (which is kind of uncommon for dreamers.. but it would certainly help with remembering your dreams, remembering melatonin is a derivative of serotonin).

Take advantage of it in the sense of lucid dreaming, but also keep in mind that it is a prime sympton of obsessive compulsive disorder (OCD).

Hope I've been enlightening.

Edit: I thought after posting that in childhood, serotonin isn't commonly so abnormally produced. I was curious, were you depressed as a child? Do you have any learning disabilities?