Pissing our way to lucidity!
I think you're both on to something, this is my new theory, I was just telling my Dad about this on Monday. He's always complaining about "at his age he's forever getting up to piss" in the night, it's no coincidence then that he's a frequent dreamer/sometimes lucid dreamer. I've noticed lately that I get up 2 to 3 times a night to piss as well, and go figure I'm usually remembering 2 to 3 dreams a night... so it's no real stretch to put 2 and 2 together and figure out that if you can awaken at 90 minute-ish intervals to go to the bathroom you're more likely to wake up during a REM period. So, to conclude, I used to not drink anything for a couple of hours before bed so I'd "sleep better" to dream, but now I've come around completely and drink 2 glasses of water every night before hitting the bed. So far it seems to be working.
http://www.vgg.com/graphics/creepout/peeFinal.jpg