Having recently gotten a Kindle 5, I noticed it had a strange screensaver after not being used for several minutes.
This feature does not make sense because e-ink does not require power to maintain nor does it suffer from burn-in.
In the interest of simplifying all things in my life I decided to turn off the distracting feature.
On the 'home' screen, that is, while not reading anything, bring up the keyboard and enter for following lines one at a time and after each line going to "Done" and deleting what you just typed:
;debugOn - disableScreensaver ;debugOff
Essentially you are just entering each line into the search field and then deleting it so you can enter the next command. It doesn't seem like it will work but it does.
Now you decide when the screensaver turns on by powering off the device.
Props to The Node.