I'm quite familiar with lucid dreaming so you could be a lucid dreamer. Dream meaning wise I could only find a similar meaning to it in my Dream interpretation book. I hope this helps (it doesn't mention stairs but spiral ones are pretty high and spiral straight up so it's similar).:
"To dream you fall from a high place denotes many troubles will follow. If you are in love, it indicates that you will never marry your present partner. To the tradesman it denotes decline of business, to the sailor storms and shipwreck."