You may have heard it before. While we sleep, our brains replay and store the days events into our long-term memories. But it can't keep everything. Of the deluge of information that pass through us each day, how do our minds "decide" what to keep and what to dump? Why can we replay the disagreement with a spouse or the promising job interview, but forget what we ate for breakfast or where we put that old sweater? A recent study says that the brain evaluates information based on future expectations. When we sleep, our subconscious sorts through our priorities and remember key points that will be useful in the future.
