The following comes from "The Success Principles" by Jack Canfield. I believe strongly in this theory and it is one of the reasons I keep books (positive, inspiring and educational books) near my bed and in the living room near the television.
Here is what Canfield says about the most important 45 minutes of the day:
Because whatever you read, see, listen to, talk about, and experience during the last 45 minutes of the day has a huge influence on your sleep and your next day. During the night, your unconscious mind replays and processes this late-night input up to six times more often than anything else you experienced the during the day. This is why cramming for school exams late at night can work and why watching a scary movie before bed will give you nightmares.