So a few weeks ago I had been in a show and then the next day I was in a gymkhana... I hadn't gotten much sleep in between because I was so exited. I also hadn't eaten much and I hadn't had much water either. At the gymkhana I fainted. (no I wasn't on my horse at the time) It was pretty embarassing. Especially since I was new to gymkhanas so I didn't really know everyone- great first impression lol! Luckily the barn owner who had taken me to the gymkhana was a nurse and she had come just in the nick of time to help me out. But yeah, just wanted to remind people of that. Get as much sleep as you can and drink LOTS of water!! Also, food might not look too amazing while your there (it seemed like it tasted SO gross just because I really didn't want to eat it and I was so exited and nervous) but make sure that you eat something.
Hope you'll keep this in mind whenever you're riding :)