Ideally, a human body needs at least 8 hours of sound sleep. This is not entirely true, for an adult body, around 6 hours of sleep per day is enough to be on the run all day and maintain a healthy body. This does not mean that you spend hours in bed just lying down and not sleeping. However, it is always a good idea to go to bed early and wake up early in the morning. If one wakes up early in the morning, it helps you feel energized and the day seems long enough to finish what ever it is that you have to finish. As you follow this habit, a cycle will form, which will enable you to go to bed at a particular time every day and you will not face any problems waking up. I would say 11.00 in the night is a perfect time to sleep and 6 to wake up.