I'm like this a lot, too, to be honest... I love reading stories, fanfiction, and pretty much any kind of fiction, and then picturing myself in that world, and how amazing it would be if it were real. I daydream putting myself in a character's shoes.

It used to be really bad, actually... I could hardly stand not being able to daydream for at least a couple of hours every day... Now, I can handle myself without it, and some days I even forget about it for an entire 24 hours (anytime that happens, I'm amazed when I realize the next day). But, I still daydream myself to sleep every night... Most of the time I accompany it with music. It just helps me get into the mood.

My social life isn't necessarily impaired by this, either, but I'd still rather not be around people for long periods of time. I enjoy being by myself much more.

Whether you should be concerned about this or not, I would say depends on how much affects your every-day life. With me, it affected my life horribly for a couple of years, before I learned to balance it out to where I could do it freely without interruption, and it wouldn't affect me during the day (which is why I usually daydream myself to sleep, now).

If it doesn't really adversely affect your everyday life too much, I honestly wouldn't be too concerned about it... but if you're worried because you do it so much, perhaps you'll be like me, where it dies down a bit after awhile.

Honestly, talking to a therapist would probably be a good idea. I wouldn't know, because I don't have access to one, but they seem to help a lot of people.

I don't know how much this'll help you, but... at least you know you're not the only one. To be honest, I didn't even know there was a name for extremely excessive daydreaming... but it makes sense.