We examined postprandial body positions’ effects on gastrointestinal motility, the autonomic nervous system and subjective comfort, i.e., whether lowering the head after a meal is beneficial for gastrointestinal motility and the prevention of pressure ulcer. We examined 10 healthy subjects and compared 3 body positions: (1) Seated upright. (2) Lying on a bed with the head at 60° and knees up by 20° (60° position). (3) Identical to (2) until post-meal; the head was then lowered to 30° (60°-30° position). Gastrointestinal motility was assessed as gastrointestinal sounds measured by sound-editing software. Digital plethysmography assessed autonomic nerve function as heart rate variability. The pressure ulcer risk was estimated as subjective comfort/discomfort using a visual analog scale. Gastrointestinal sounds increased post-meal. The 60°-30° position showed the highest number of sounds and longest cumulative sound duration. Post-meal, sympathetic activation was suggested in the 60° position, whereas vagal activity was relatively preserved in the 60°-30° position. The 60°-30° position was the most comfortable, and the 60° position was least comfortable. Lowering the head after a meal is beneficial to augment gastrointestinal motility and decrease the pressure ulcer risk. The 60° head-up position increases the pressure ulcer risk.