Comment by dspillett

> sleep was the training of our neural network with all the prompts of the day

Periods of sleep certainly seem to be used in that sort of way, but that is an extra use evolution found for the sleep cycle once it existed rather than the reason sleep developed in the first place.

There are a number of things that seem tied to, or at least aligned with, our wake/sleep cycle that likely didn't exist when sleep first came about.