Dominant western culture sees early rising as a virtue and staying up late as a vice. This seems to have strongly agricultural roots. Back when we lived in a predominantly agrarian society, work was mostly farmwork. A number of important farm animals are early risers, and so farmwork is best done early in the day and during daylight hours.
This, unfortunately, has led to a misconception that the best (and in some people's eyes, only) way to have a healthy, successful life is to get up in the morning, work during daylight hours, and go to bed in the evening. Modern society still expects everyone to do exactly that, even though many of us no longer live and work on farms. Standard school/work hours are between 8-9am and 4-5pm; standard mealtimes are 6-8am, noon, and 6-8pm. Society frowns upon those of us who deviate wildly from that schedule, and deems it acceptable to mock us.
But it wasn't always that way. There's a theory that people in different stages of the human life cycle are adapted to sleep during different parts of the day, such that someone in any group of humans will be awake and alert to surrounding dangers at all times. Teenagers and young adults, for example, tend to be awake all night and sleep all day, while older adults are awake during most of the day and evenings and sleep at night, and our wisest are most often awake in the early mornings with short naps during the day and much sleeping in the evenings. In my opinion it would be much healthier if we stopped insisting that everyone adhere to the exact same schedule - from very young to very old - and let people pick their own optimal cycles for productivity and sleep.
Early to bed and early to rise will make some people healthy, wealthy and wise. Early to bed and early to rise will make others merely sleepy, grumpy and hungry. As a friend said to me earlier today, the truly healthiest way to live is to be happy. Really happy. To do everything in your life the way you want it (provided your chosen life patterns aren't self-destructive).