One of the best ways to get control over GERD, especially if you experience heartburn while you sleep, is to sleep with your upper body elevated. You don't have to sleep standing straight up on your feet, but you also don't want to just prop up your head -- it won't help. The esophagus itself (which runs from the back of the throat down to just below your sternum) needs to be slanted by keeping your collarbones higher than your hipbones.
One of your allies in your struggle with GERD is gravity, which makes it harder for stomach acid to work its way upward. Other allies include saliva (which essentially washes regurgitated liquid back down the esophagus) and the act of swallowing. But when you sleep, you're all on your own against the forces of GERD -- no gravity (your esophagus is horizontal), no saliva production and no swallowing in your sleep.
To help keep stomach acid out of your esophagus at night, you can do one of several things to elevate your upper body. You can use pillows or a foam wedge to prop yourself up, or you can use wooden blocks or other objects to lift the upper part of the bed so that the entire bed rests at an angle.