Lie on your side on a flat pillow and your neck tilts toward the mattress all night. So you fold the pillow, stack a second one, wedge an arm underneath — and wake at 3am shaking the pins and needles out.
The Meyoru's raised curve fills the gap between head and shoulder, so your neck stays level and your arm finally gets the night off. One shape, doing the job three workarounds never could.