Figure 3. Photographs of a 26-year-old normal-weight (body mass index, 21.5 kg/m2) male patient with moderate obstructive sleep apnea syndrome (apnea-hypopnea index, 15.9 events/h) using either a regular pillow or the head-positioning pillow (HPP).

(A) Original image of the HPP pillow. (B) Cross-sectional image and materials used for fabricating the HPP pillow. (C) The median portion of a regular pillow supports the head and neck in the usual position. (D) The median portion of the HPP is the highest point that can help keeping the head and neck in the sniff position and maintaining the patent airway in the lateral position. (E) The bilateral paramedian portions of a regular pillow have the same height as the median portion and provide no additional benefits during lateral sleep. (F) The bilateral paramedian portions of the HPP are its lowest parts; such design can ultimately promote head and neck rotation to the lateral sleep position and maintain the patent airway.