Yeah. Perhaps animals are the first organisms that developed the ability to be awake, not the first that developed the ability to sleep.

By the way, even Cnidaria (jellyfish etc) exhibit sleep-wake cycles [1]. They don't have a brain, but they do have a nervous system. Maybe the first animal with nervous system (a common ancestor of Cnidaria and Bilateria) was the first to have a sleep-wake cycle.

I don't understand the current research on mitochondria, but it sounds as if sleep has to do with how neurons work.

1: https://link.springer.com/chapter/10.1007/978-3-031-62723-1_...