We have a handy analogy in the computing world, in that stop-the-world and concurrent garbage collection algorithms both exist. If sleep is pure garbage-collect

We have a handy analogy in the computing world, in that stop-the-world and concurrent garbage collection algorithms both exist. If sleep is pure garbage-collection, then I don't think there's any strong reason to expect it to be required of all possible mind designs. However, it seems increasingly likely that the empirical question may be answered at some point soon!