[cardine]

You are conditioned to overeat because your body can store the excess energy in the event of future needs.

The body is expecting such a future need as in our past there were often periods of food scarcity. Since in our modern society this food scarcity doesn't exist, the body overconsumes, preparing for a future that will never come.

We do not have such a mechanism for storing infinite water, so we do not crave an overabundance of water.

I think you are thinking about sleep on the wrong axis. It is not whether it is a superstimulus; it is whether your body can store an abundance of it for a future anticipated need.

I would argue in this case, sleep is much more like water than food in this way in that there is a very small amount of sleep (possibly zero) your body can effectively stockpile.