According to this article on the BBC some of us can't help being a lark or an owl. It may actually be genetic, yup, it's your dad's fault if you leap out of bed waaay to early in the morning.
"We recognised this was a strong genetic trait. We found the mutated gene resided near the end of chromosome 2", says Louis Ptacek.
They knew that if similar genes were mutated in fruit flies and mice the circadian clocks speed up. The mutated gene made a different protein that affects the rhythm of the clock.
They also study families of extreme owls, with Familial Delayed Sleep Phase syndrome. And they think this was due to a different mutation in the same genes.
Mutations in other genes have been found in other families with advanced or delayed sleep patterns.
We all have internal circadian clocks - the master clock is made up of thousands of nerve cells in the suprachiasmatic nucleus, a wing - shaped structure located in the hypothalamus, at the base of the brain.
The hypothalamus controls all kinds of bodily functions, from releasing hormones to regulating temperature and water intake.
This internal clock is reset every day by light. You might expect that since the earth's day lasts 24 hours, everyone's clocks would run to a similar schedule.
So... what are you? Lark or Owl?? (I'm a total owl btw...)