There is a new book out by David Rock called Your Brain At Work. I have been awaiting this book's release for a couple of months because it was touted to be a great book on neuroscience that actually can help you figure out how to work better. They were right. This book is great.
One of the coolest descriptions in the book is Rock's description of the Prefrontal Cortex; which is the part of the brain that helps us decide what to do, among other things. He describes the prefrontal cortex as like a stage that actors use. The actors that enter from the sides are the external stimulus that we see, experience, etc. The actors who enter the stage from the audience are the conversations we have going on with different parts of ourselves. All of these "actors" can interact with each other. When we try to remember something from the past, depending upon how far back or how hard it is to remember, it is like a person sitting in a dark seat way off in the corner of the theater that we have to search for to shine a light on and talk with.
Why is this analogy important? Well each of these interactions or actions, whether it is the actors interacting on the stage or the act of remembering something, takes up our brain's energy. Come to find out that stage is TINY. It can only hold about 4 things on it at the same time. When you and I open our computers and the emails flood in, and we add to that all of the things we need to do while taking care of our home lives, schedule, hobbies, exercise, etc...we can become instantly overwhelmed. Too many actors on stage! That's why sometimes we'd rather just shut the lid and go eat breakfast, or go back to bed.