Such as?
So I think lucid dreaming is not necessarily a problem in itself but forcefully training yourself to do it can be rough going.
Personally I've found them deeply disturbing. Throughout my life I have experienced moments of sleep paralysis at most on 10 occasions. They've left a big impact though, and I sympathize with anyone who has the misfortune of feeling as though you are trapped and unable to move.
After watching the film "Waking life" I spent a long time thinking about lucid dreaming and perhaps maybe had 1 or 2 myself. I had never connected the two however, definitely food for thought.
When I actually learned what it was I tried lucid dreaming and stuff with it. But, I always find the feeling uncomfortable. I don't like not being able to move or do anything while your dreams mix with your bedroom.
It doesn't happen so much now. Every once in a while if I wake up in the morning and go back to sleep, the second time I wake up it'll happen. I don't tend to sleep in any more and once i'm awake I get up.
I don't know if it's related but i've always had problems sleeping. When I was young I was scared to sleep, even as a baby i didn't sleep well. I can usually fall asleep alright now but the slightest noise in the night wakes me up and I still feel wary about losing conciousness.
Makes it very difficult to keep track of things.