What is the superlative of Sleep?

There isn't a true superlative form of "sleep" in the traditional sense. Superlatives are used to compare things, but "sleep" is a state, not something you can compare.

However, you could use phrases to convey a similar idea:

* "Deepest sleep" - This emphasizes the intensity of the sleep.

* "Most restful sleep" - This focuses on the quality of the sleep.

* "Most rejuvenating sleep" - This highlights the benefits of the sleep.

You could also use more creative language:

* "The sleep of the dead" - This implies a profound sleep.

* "A slumber so profound" - This emphasizes the depth of the sleep.

The best way to express the superlative of "sleep" will depend on the context and the specific meaning you want to convey.