> It's still very odd that no species has ended up evolving a continuous maintenance system that can run while conscious

Great point. Afaik, our bodies do preserve energy when we sleep/rest. A few questions that needs to answered first:

- will gains of 24/7 hunting/foraging offset the extra energy costs? Lions sleep 16-20 hours a day, according to the internet.

- do continuous maintenance systems imply duplicate systems? If so, I have a hunch that even a mere 40% increase in energy expenditure would quickly undo the gains in waking hours.

> It's still very odd that no species has ended up evolving a continuous maintenance system that can run while conscious, the benefits when hunting other animals that need sleep would be enormous, so there has to be significant evolutionary push for it.

I disagree. Endurance hunters walk an animal down throughout a single day. Sleep isn't the bottleneck. Efficient bipedalism and sweat are enough.

There's a similar mechanism called USWS https://en.wikipedia.org/wiki/Unihemispheric_slow-wave_sleep (Half of the brain remains awake while the other sleeps, not an expert so please correct if wrong)

The fact they electrically signal via chemical analogs fuelled by immersion in nutrient bearing fluid that also accretes waste products, yet is kept separate from the primary loop of the cardiovascular system by the blood-brain barrier?