Left side: best overall
Improves digestion, reduces reflux, lowers snoring and supports glymphatic clearance.
Back: best for spinal alignment
Excellent for back pain but worsens snoring and apnea in most people.
Stomach: worst for the neck
Forces head rotation for 6–8 hours. Switch to side sleeping if possible.
Fetal position
Comfortable but can restrict diaphragmatic breathing if curled too tightly.