system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 how do our bodies naturally prevent us from falling off skinnier sleeping surfaces when we’re used to more space (like taking a nap on a sofa)?
gpt
Even while sleeping we have a “sense” of sorts to know we’re on the bed in relation to the edge that prevents us from falling off. This develops into adulthood so kids can still fall off occasionally.