Sleep

Here's a story about how REM sleep can help solve problems, with Keith Richards and Mozart mentions, and this quote:

>>She theorizes that it's a time when the brain's neocortex, the part of its gray matter associated with thinking, is free to integrate fresh information and malleable ideas and memories into a new synthesis: a eureka moment. The process works especially well for musicians, scientists and artists whose challenges are analogous to the neocortex's, Mednick said. That is, to make new connections among bits and pieces of familiar elements.<<