This is actually a common problem. It's because the logic centre of your brain is asleep. Do a couple reality checks (pinch your nose, look at a clock, look at your hands) and try yelling "This is a dream! I can do whatever I want!"
My newest technique is to yell "Ragnarok", "Armageddon", or "Apocalypse" whenever I think I'm dreaming. They all cause major distortions and help me realize I can do whatever I want.