[batgaijin]

I always wondered about how split-brain theory would work into this...

I mean there are stories of people with half their brain removed who are fully functional (I think? I can't find a source atm).

I wonder what would happen if half your brain could be on/off and switch?

Also you'd think that any mutation optimizing for time awake would have decimated the other creatures? I don't get how evolution has conquered everything but sleep.

[whateverfor]

There are actually animals that sleep half a brain at once: all the marine mammals. A dolphin can't just fall asleep underwater (it will drown), so it sleeps half at a time.

There are creatures that sleep very little (Giraffes, etc.) But there's large benefits to sleep, and for most animals it's worth the cost, especially since you don't want to burn piles of calories during non-peak hunting/foraging hours anyway.

[soneca]

On that post about a bird that fly for 6 months in a row there were a discussion about the sleep in animals. Some of them are able to sleep alternating one half sleeping and the other aware of the environment. And there is speculation if that bird could sleep while flying.

I think half brain awake is not enough to have a fully functional life. I also heard about people losing part of their brain and adapting to deal with it. But that doesn't mean a brain doesn't need that part. It is like the fallacy of using only 10% of the brain. The brain is very well used and optmized for performance, if you lose part of it, it would adapt to compensate what is missing, but it will not be optimized anymore.

Disclosure: just guessing here, I have no scientific knowledge or background at all to support these claims of mine.

[dkersten]

In the case of the bird, it may not need fully optimized brain to fly. So it might be acceptable to have reduced brain performance as a tradeoff for longer awakeness, especially if you could recharge under reduced performance and then go back to fully awake (and rested).

[drited]

The people who have had half their brains removed (Hemispherectomy) and are functional had it removed when they were very young and the other side wired to adapt. Depending on age of operation, there may be more or less significant impairments for life.

For humans with 2 healthy hemispheres, as far as I'm aware better imaging is revealing that split brain theory is only partially correct for many of the processes that were formerly thought to happen in one half only. Recent imaging has shown that the other half is still involved, albeit in a less widespread fashion.

[emiliobumachar]

>you'd think that any mutation optimizing for time awake would have decimated the other creatures?

Maybe the specialization into day/night has something to do with it. The decimator would need to stand their ground against nocturnal creatures at night and diurnal creatues at day.