Lay off the late night cheese on toast man.

If you smoke cigarettes, try nicotine patches while you sleep, they really take the edge off nightmares.  Or try some herbal nytol.

If its worse than that, go see a doctor or try some sort of lifestyle change.

I used to have loads of bad dreams, but I've defeated them all one way or another.  Now I barely have time to dream, I just pass out then drag myself up for work the next day.  

nicotine patches gave me the most vivid and frightening nightmares, so perhaps different people have different reactions to those.

I'd try a dietary adjustment, mate. It's a fact that the brain's functions are all controlled by various chemicals, on the off-chance that something in your diet could be affecting you, it might be worthwhile to try laying off red meat, stimulants (tea/coffee),chocolate....just plenty of fruit and veg (might need to avoid wheat too, though!)... give it a try for 2 or 3 weeks, if it works, you can slowly re-introduce your usual foods until you identify what triggers your nightmares. (for me, venison brings about the most horrible nightmares, if i lay off red meat I sleep like a baby).

and for godssake don't take DrRicky's prescription

I want to try the nicotine patches!!!