Early to bed, early to rise

Last week, I have been trying to change my routines. Usually, I went to bed very late, sometimes may be 2 o'clock in the morning. Last week, I talked about it with a doctor, he said my routine is very harmful, and I should sleep earlier, the best time for sleep is not later than 11 o'clock in the night when the hematopoietic stem cells(HSCs) start to work. So I tried to change my routines, and in the first day, I cannot fall in sleep at that early of a time, because in myusual time, I was playing my Ipad. The first morning of getting up earlier is also very hard, because I got up an hour earlier than usual time. Fortunately, I stuck to it, and now I feel very tired when it comes to 11 O'clock, and I will be awake at 7 o'clock in the morning. I think it is good for my health.