I’ve never had a patient ask about sleeping position for arm liposuction in my career. I’ve done 8000 liposuction procedures so I have done arms quite a few times. patients typically just sleep in whatever position is comfortable while healing. once you’re healed you should be comfortable sleeping in any position.I don’t think you’re sleeping position matters but putting direct pressure on the area for the first few days after treatment will be uncomfortable.Best,Mats Hagstrom MD