Because, even though you are lucid, you may not grasp that it isn't real, and you may feel compelled to go along with the plot anyway. [/b]
I was under the impression that the definition of a lucid dream is one that you consciously know that you are dreaming and can therefore take control of the dream; that if you still believe that the dream is reality then you are not in a lucid state.

If this is not the definition, then what is a lucid dream? How can you be lucid but not be in control? I sometimes have dreams in which I can impulsively alter the situations in which I am participating but I would not consider them lucid because I am not actively in control.

Enlighten me.

Now they are not truly nightmares cause i'm not terrified, but i am scared, because they are some of the most realistic dreams i have ever had.[/b]
I would try using the situation as a dreamsign if possible. Are you writing them down afterwards? How often do you have these nightmares? Is there something bothering you in your life? Is there something you are trying to hide from people around you? Much stress?

Nightmares are common. Try not to let them bother you - or attempt to use them to become a dreaming advantage in order to become actively lucid.