So I have a planet with multiple species on it. My planet is tidally locked. I know it is generally thought a tidally locked planet couldn't harbor life because of the extreme temperatures, but my argument is that it is theoretically possible if the planet has a thick enough atmosphere, which helps with cooling, and if there is steady airflow from light side to dark side. This does cause very extreme weather, especially around the area where it goes from light to dark, but still, it keeps the temperatures survivable most places on the planet, except the spots closest to and furthest away from the star.
But here's my question. I am assuming on a planet like this, circadian rhythms would not have evolved since there is no day night cycle, and therefore species would not sleep, at least not in the way we do. The planet is at a tilt, and therefore some latitudes do have daylight during summer and night during winter, so in those places I can see hibernation being a thing. But otherwise, I don't think they would sleep.
So my question is what could replace sleep as a restorative process for their bodies? Entropy would still cause their cells/neurons to degenerate, and so I imagine they would still need some kind of regular, restorative process to keep them functioning. What could this be? How exactly does sleep help restore our own brains? If I understood how that works, I might be able to come up with a reasonable process to replace it.