Sleeping is very important, not only for your heart but for your entire body. It makes you feel healthy and younger with more energy. It is very important that you make a habit of sleeping because benefits are better doing it in this way.
I reccomend, like a famous doctor said, that you sleep according to your personal needs, here is a reccomendation for sleeping:
From 8 p.m. to other day , you will gain more youth.
From 12 A.M. to other day, you will rest but not will gain more youth
Ideal Case would be according this doctor, i don`t remember his name,
From 10 P.M. to other day
That`s all according to your needs and schedule, but if you do it in another way, it is acceptable because all of us have different needs and personal situations.
Here is a link that you could use for achieving better results with sleeping :