[header] How to pretend to be asleep [title] Slow your breathing. [step] Why do you think people look so peaceful while they're sleeping? When you're asleep, your breathing slows down slightly. [substeps] You can practice a breathing exercise to relax and slow down your breath. 
Try breathing in through the nose for a count of four, and then out through the nose for a count of four. When you are sleeping, your heart rate also slows.