system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 what is my body doing in the "Aaaah, AAAAAAH-" moment of a sneeze? Why does it vary in length?
gpt
When you start to sneeze, it's because of some sort of irritation in your nose to release histamines. When histamines reach the nerve cells in your nose, it tells the brain to start what I'll call the Sneeze Sequence.

The "Ah" sound you make is due to your body reflexively taking a large breath. During this time, the muscles in your throat and nose expand, creating an opening that allows large amounts of air to pass through. Then, your chest muscles rapidly contract, forcing the air out of your lungs and through your nose. 

The variation in length is based on personal anatomy and how your brain handles the Sneeze Sequence. It's different from person to person.