Agreed. I get up every morning around 6am. Some mornings I get up at 5am for a group workout thing, but it's mostly around 6am. I'm normally in bed right before 10 because I have found out through experience that I need ~7-8 hours of sleep/night.

I can shift this a bit, say go to bed around 11 or 12 and sleep later, but I am not nearly as productive in the mornings then. If I push this more extreme and say go to bed at 2-3am, even if I sleep until 10 or 11, I am wrecked the next day. I actually feel worse than if I only got 6 hours of sleep instead, but went to bed earlier.