Risk of screen burn in?

When asking Mycroft to “go to sleep” the screen displays mycroft’s sleeping face expression, but never turns off. Isn’t there a risk of the picture burning into the screen? Is there a way to automatically turn off the screen after a certain time of inactivity? Since the screen of the dev-kit is not an OLED display, the black background is still pretty bright and therefore need ideal when the device is placed in the bedroom.