This topic recently came up at the FLANN workshop [1], and seems to periodically be rediscovered [2,3,4] in different contexts. While some have speculated about the biological role it plays (e.g., Pearlmutter & Houghton [5]), we still lack a conclusive theory of sleep, but the convergent evolution of this specific phenomenon across the animal kingdom and the fact that deprivation is inevitably fatal seems like an important clue.

[1]: https://flann.cs.yale.edu

[2]: https://www.cs.toronto.edu/~hinton/csc2535/readings/ws.pdf

[3]: https://arxiv.org/abs/1711.02282

[4]: https://arxiv.org/abs/2006.08381

[5]: https://mural.maynoothuniversity.ie/id/eprint/1653/1/Hamilto...