This tip is from Eric Oehms, ATC.

“One tip that I tell my athletes when needing to elevate a lower extremity during sleep to decrease swelling.  Instead of using pillows that get matted down or end up on the floor, elevate the mattress at the foot of the bed.  My suggestion is to use a dresser drawer and place it between the mattress and box spring at the foot of the bed.  Your leg will stay elevated the entire night.”