Humans would be very different. We need sleep because of our nature vis a vis the nature of the world. So it depends on how our nature would be different such that we didn't need sleep. It would have to be something very radical, considering all animals sleep. And we'd probably not not nearly as interesting because we'd be less alive/conscious. Fully living beings need regular breaks from the harshness of physical life. Since we'd be less alive (if it would be possible at all--that's the only way I can imagine it), we probably wouldn't have been smart enough to dominate and decimate the natural world, so the world would be very different, more like it was a hundred thousand years ago.