Let me just start by saying - these thoughts were not prompted by Inception. I've thought this for a *long* time. I even believe sometimes that Inception was a message from my subconscious trying to tell me that my theory is correct.
So here is my theory - I believe, in reality, I am actually in a deep coma and this life is my serious coma dream. I think I may just be reliving life I've already lived in this dream (dejavu) and that in reality I'm laying in a hospital bed, my beloved husband ever present at my bedside, my children (those who aren't in comas themselves) visiting on the weekends. You see, in this reality, people are all getting sick and falling into the same type of coma I'm in. The doctors really can't do anything for you except try and keep you alive until (in your coma dream) you die.
There is only one way to survive this illness - live out your life in your dream, die in your dream, and then you have a 50/50 chance of waking up. The other chance is that you'll just die forever. Fun theory, huh?
There is other stuff, too. Since your body is gradually failing in reality (it just gets worse the longer the dream goes on, e.g. OLD AGE) the doctors really are working constantly to keep you alive. At least...they're working constantly to keep me alive. Here's what my original train of thought comes in -- HICCUPS. I'm pretty sure hiccups are the doctors trying to resuscitate your heart. Have you not noticed (or is it just me?) that your chest jerks around like in the TV shows? Just me?
Anyway. I also believe other small annoying things (like banging your elbow against a door) are the doctors and your family trying to wake you up. They do it in reality, and it just associates itself to fit into your dream. That's why you do really stupid things sometimes like just walk into the corner of a table. Not your fault. It's Reality's Doctors. Sure, they're trying to save your life, but I think we can all agree they are REALLY annoying.
Chew on that for a little while. :)