To my surprise, the symptoms I felt were mild. The first thing I noticed was that my vision was a little fuzzy, and I wrote that down. Then I began to feel a little lightheaded, but not dizzy. I wrote that down. There was also a strange, warm feeling in the back of my neck. Finally, there was just an overall sensation of labored breathing, and an odd feeling in my chest. I just didn't feel right, but it was not an overwhelming sensation. FlightSafety limits the time at 22,500 to under seven and a half minutes, but most pilots so far have recognizable symptoms in under five minutes. After about five minutes at the simulated high altitude, the air I was breathing was switched to 100 percent oxygen. Recovery was very rapid, and it was then that I noticed the color wheel brighten up. I had noticed that the colors had lost their distinction while at the simulated high altitude, but with oxygen back, the difference was sharp.