I do a lot of intense mental work. Periodically, I take a break and do a different activity for a while: listen to part of an audiobook or watch something on TV or play a game. There is an old saying that “a change is as good as a rest.” I know that when I take a break and change my activities, I often return to the first activity with renewed interest and energy. My question is: are rest and sleep interchangeable for the brain? Is a change as good as a sleep for the brain?