When the touchscreen is dimmed, you can still use it. Tap a menu choice or button, that action will be carried out, and the touchscreen will brighten.
To light up the touchscreen, tap the touchscreen, tap the Home button, or press and release the power button.
Sleep:
To save power, your NOOK sleeps after a period of inactivity. It turns off its touchscreen and wireless circuitry. While your NOOK is sleeping it displays a screensaver image on the reading screen. Configure the sleep timer in Settings. Tap settings > Display > Sleep timer.
Do not rely on sleep mode when you should turn on Airplane mode (for example, on an airplane).
To wake your NOOK from sleep, press the power button briefly (for a second or so) and release it.
When your NOOK awakens from sleep, you are right where you were when it went to sleep.
After 72 hours of sleep, your NOOK turns off automatically to conserve battery charge.
For normal use, because the reading screen does not consume power, just let your NOOK sleep. It takes longer for your NOOK to turn on from off than it does to wake from sleep. Also, by letting it sleep instead of turning it off, your NOOK wakes up periodically to perform tasks like downloading new content.
USB drive mode:
When you plug your NOOK into a personal computer, it connects to USB. This puts your NOOK in USB drive mode. In this mode, you can access files on your NOOK from your personal computer, but your NOOK is locked until you disconnect it from USB.
Power Button
The shiny metal strip at the top of your NOOK is the power button:
NOOK User Guide | Power and Charging | 16 |