Inclined bed therapy is where one’s bed is raised at the head end with a gentle 5 degree downward slope. This can be useful in disorders such as spinal cord injury, back pain, acid reflux or GERD, sinus and respiratory disorders, sleep apnea, poor circulation.
Sleeping on a flat surface is not normal in the animal kingdom. Most mammals will choose to sleep with their head uphill if they can. Beds found in the tombs of ancient Egyptian royalty were almost always at a 5 degree incline.