system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do we get the uncontrollable urge to stretch? Why is it connected to yawning and how does it happen?
gpt
Stretching helps stimulate circulation and manage muscle tension. Likewise, yawning flexes the ear canal and dislodges excess earwax. It's kind of like an itch. The body has a maintenance issue that needs to be taken care of so the brain suddenly gets the urge to do something about it. The exact connection is complicated but it's sufficient to say your brain comes with a set of instincts on how to maintain the body. It's not complete but it helps.