I have the same thing. Sometimes i end up sleeping for 20-24 hours, if my parents don't wake me up. Mostly i wake up afther 14-15 hours, but then i just fall back to sleep again in matter of minutes. Dreams are quite vivid at so mutch sleep, and very easy to remember for me. I actually beleve 80% of my lucid dreams where in that period, might explain why i don't have them now, since i need to wake up early these days.

I wouldn't worry to mutch about it, if i was you.. The only negative thing is that it can effect your waking life a little bit, if u do this everyday, and it can mess your sleep schedule up.