I am thinking this sleep research begins too high up the evolutionary ladder. The conclusions reached by the researchers could well be substantial even compelling but we know from many other areas of evolutionary biology many biological systems evolved for a particular function end up performing a completely different function in the face of environmental change.
We need to return, as far as that is possible, to the origins of sleep components, not just on the human animal but in all organisms that move into the sleep-state on the day/night scale.
Was sleep a physical survival mechanism? Why do we naturally sleep at night? What is the original basis of falling comatose for eight hours each twenty four hour cycle?
The underlying mechanisms of sleep need to be researched before we can add layers of additional material that may have evolved recently, secondary to the original function.
This from The Guardian:
Discovery that sleeplessness causes neurons to become ‘muddled’ with electrical activity could help develop new treatments for mental health disorders
In a study published on Tuesday, researchers show for the first time that sleep resets the steady build-up of connectivity in the human brain which takes place in our waking hours. The process appears to be crucial for our brains to remember and learn so we can adapt to the world around us.