Steve Pavlina also talks about this in another post, and I did it for a month to train myself to get up at 345am, which I did with 99% consistency for the next 4.5 months [1]. Starting in Jan, I've been getting up at 430am instead, but this technique of training your subconscious is one of the most effective hacks I've ever tried.

1. http://ryanwaggoner.com/2011/01/135-days-of-getting-up-at-34...