All animals sleep

Dolphins, Lions, even worms sleep. The brown bat is the record holder for the most slumber with 15 hours of sleep per day while giraffes get the last sleep with only 4-5h each night.

The point is that no animal can forgo sleep. Over thousands of years of Evolution, sleep remained. Even when it is hours of being in a vulnerable state without consciousness. That must mean that it is not only not as practical as staying awake but even more. Sleep must have such a multitude of benefits that it is worth spending a third of the waking time in that state.

Additionally, no animal deprives itself of sleep, only humans do.