we evolved
in this world with a 24 hour day 8 hours is the average dark period. Dangerous to move around then, so sleep!
Others e.g. bats, decided that night work was preferable and evolved otherwise. Some creatures like Swifts do not sleep at all in our sense, spending almost all their lives in the air!
We exist as we are because of successful strategies adopted by our ancestors! You're not great, they were!