Aw, is your friend on the forum too? I had a friend who had abilities like me too when I was your age. I feel so damned old now . . .
Anyhow, the nightmares are likely your subconscious mind picking up on negativity in the world, your abilities are much stronger when you sleep, and so they will activate at deeper level.
What you can do to stop it is go to a homeopathy shop and purchase Belladonna 200ch. You take 10 drops of it at night and then your mind can't roam outside of your own psyche and so you won't pick up things in your sleep.
Belladonna is also a natural homeopathic cure for nightmares, but if you're not having nightmares it causes them.