No. Sleeping is the most difficult part of what I do, relaxing afterwards. Letting things go. Thinking isn't something you think about. It comes naturally. Thinking involves many things. It involves being an observer. It involves analyzing things, taking in what's around you in the world and finding how to make it inspire your work or turn it into a lesson to teach your children; it's paying attention to details. That's what thinking is: processing.

Ref : http://www.interviewmagazine.com/music/madonna-1/#page3