-has to support your neck and head
-not so soft nor hard pillow nor mattress
-when you lay down on a side on a mattress with a pillow, your nasal septum (nose center) has to be parallel to the mattress.
-your head and neck can not tilt nor wedged, rotated (snoring position or teeth grinding).
-do not sleep on tummy
-if you sleep on your back, pillow has to be lower than side sleeping pillow height.
-you always have to think how you can sleep 8 hours with a pillow. You have to neutralize your body to sleep for 8 hours.
-both hands have to be lower than shouler lines
-can not put your arm below the pillow
-bend knees a little bit
-put your arm a little bit foreward to shoulder line