> if the AC is more than 68F I'm hot and uncomfortable
For sure! 68ºF is usually the right spot. During the winter, I let my bedroom get to 64ºF or lower. But then I love having a ton of covers on and wearing a knit cap to bed. I sleep so much better in the cold under covers. That's why I laugh at 78ºF (26ºC) being called "cold."
Fahrenheit vs Celsius, just convert to the metric system already America!
Living in the equator is hot that I set my aircon to 16°C. But if I keep it up for too long I'll get a cold, so I keep it running for about an hour and let the fan circulate the cold throughout the room.