I've been having them for as long as I can remember - I vary though, from 4-5 a week, to a week or two without any. Generally without Reality Checks - the dream will start and I'll think "Oh - I'm dreaming.".

I've found that most of my dreams come when I wake up in the morning, decide my first lecture isn't that important and reset the alarm clock - I generally put my head down, slip straight into the dream and know that I'm dreaming.