As for the 6 a.m. wake-up, that window allows for eight hours of sleep. Now, not everyone needs exactly eight hours a night, but somewhere between 7.5 and 9 hours is usually enough for an adult to feel sufficiently rested when they wake up in the morning. (Note that if you’re sick, menstruating, or doing a lot of rigorous exercises, you may need some more.)
If your work schedule or family life doesn’t allow for sleep between 10 p.m. and 6 a.m., it’s not the end of the world. The more important thing is that you do your best to stay consistent. The more our body gets used to a sleep-wake schedule, the easier it will be to fall asleep at night and wake up refreshed in the morning.