Barnes & Noble nook User Manual page 20

The setting that specifies the time period is Touch Screen Timeout Period.
To turn on the touch screen display, tap the Home button one time or double-tap the touch
screen.
Sleep
After a configurable period of inactivity, your nook goes to sleep. This is to conserve power.
When your nook is asleep, the touch screen display is turned off and a screensaver image is
displayed on the main screen.
Do not rely on sleep mode when you should turn on Airplane mode (for example,
on an airplane).
To awaken your nook from sleep, press the power button briefly (a second or so) and release
it. This awakens the nook, exits the screensaver, and returns you to where you were when the
nook went to sleep.
Your nook also goes to sleep when you close the optional cover that is available from BN.com
or a Barnes & Noble retail store.
Mass Storage Mode
Mass storage mode lets you manage B&N and personal content on the internal microSD card
and supplemental microSD or microSDHC card, if there is one.
You cannot simultaneously manage files through USB and use your nook, so the device is
locked.
nook User Guide 20