There are now numerous brain studies which indicate that sleep can do wonderful things for you. Apparently, sound sleep affects positively gene expression and helps the myelination (or maturation) of neural fibers connecting distant brain regions (which is essential for neural and mental integration); plays a key role in neural restoration and washing away the toxins built in the brain during a stressful day; facilitates the consolidation of long-term memories; etc. All these findings should perhaps prompt the obvious question:
What does chronic sleep deprivation does to your brain? Or to the brains of kids which need to develop those neural pathways and build up background frames of reference? But perhaps we should better not think too much of this, as we could lose even more sleep.