But mobile internet threatens to take away these periods of extended idleness, thus threatening creativity.
From my own experience, when I'm tired I want simple, easily-digestible input - stories to read, video-games to play, websites filled with fresh user-nominated content. Without internet access, I'm just bored, not creative. On the other hand, when I'm well-rested and feeling alert and active, I can't not be creative - the idea of sitting down and passively consuming ideas would be just as torturous as being creative while tired. I've got to write code, take photos, go for a walk, something.
If worst comes to worst, we'll always have the shower and the toilet as enforced creativity timeouts. :)