Dell XPS 18 (1820, Early 2014) - Manual (Page 24)

24 │ Using Your Computer
Turning Off the Screen
Using the power button:
Press and release the Power and Sleep/Wake button
to turn off
the screen.
Using Charms:
Swipe from the right edge of the display to access Charms.
Touch Settings
→ Power → Sleep to turn off the screen.
NOTE: If your computer is in a sleep state (computer is on, but
screen is off), press the Power and Sleep/Wake button
or
Windows button once to turn on the screen.
Turning Off Your Computer
Swipe from the right edge of the display to access Charms.
Touch Settings
→ Power → Shut down to turn off the
computer.