I did it twice ages ago, I noticed I was in a dream after realising things that didn't make sense, I was on a bus to school when in reality it was the holidays.

At the time I was also staying at someone else's house so I had that weird feeling of sleeping under a different roof.

Also the whole time I was on the verge of waking up, I could feel my body and had to be careful not to move it while moving in my dream.