It's a network of computers with GPUs, so there's no reason it can't sleep at the same time it's awake. Just a continuous "sleeping" process going on in the background, incrementally updating the model. No need for the "thinking" process to be "unconscious" while the "sleeping" process runs. Anthropomorphism confuses everything. There's no such thing as "offline hours" because the Earth is a sphere and the United States is not the center of the universe.