why we must sleep very early can make us better?

A good sleeping habit is very important for our health and study.When we have enough sleeping time,our body will rest properly and prepare for the next day's work .So we will be energetic in a day and ready for everything.If we don't sleep well ,we will be so sleepy that you can't concerntrate your attention on your study .As a result,you learn little in a day.As for me,I often go to bed at 22 and get up at 6 in the morning,that is to say,I have 8 hours to sleep ,so I am healthy ,energetic and ready for my study every day.