It sounds fake, but it might genuinely be your genes. Scientifically the natural tendency to sleep at specific time is called your chronotype and it's semi-genetic (it also changes with age and possibly few other factors). Not only that, it also affects your alertness: morning people usually have the highest alertness just after waking up and it gradually declines throughout the day, while evening people usually wake up with very low mental functions, but then their alertness slowly rises and hits its' peak around 5-6PM.

So if you ever wondered how it's possible that you always wake up feeling like shit, while others talk about how they're so full of energy in the morning. That's how. They're literally built different.