It would make sense if there was a monocausal explanation of why ancient ancestors started sleeping, but then other body functions started making use of the sleeping system since it was at hand.
I tend to believe that our ancestors didn't start sleeping, they started waking up ! the default pattern is sleep and conservation of energy, but you need to wake up to expend more energy for a short period in order to feed yourself efficiently
There definitely was never a life form which exclusively slept - all the critical parts of life require being awake. Life that didn't sleep, however, is possible.
I don't think they meant "Modern" sleep. I think they meant "Only brief periods of highly energetic activity before returning to the usual activities were precursors to our modern consciousness/wakefulness"
That is also what I am referring to. Energetic activity is required to live and to reproduce, those are the normal activities. An active creature may have evolved a state of dormancy for various reasons, but there was never an organism in a state of pure dormancy.
Sure, but probalistically some will! So if 99.9% don't lose their dormancy state, that small percent will carry the organism's lineage on. Obviously I'm generalizing, but I think my original point stands!
Yea, but at some point this is probably gonna strain the colloquial definition of sleep. So I went for one of the oldest and perhaps simplest animals around, to examine the "creature" angle in extrema.
Maybe not 'exclusively' slept, but koalas[1] sleep for a majority of the day (16-20 hours) in order to digest highly toxic eucalyptus leaves which constitute the main portion of their diet.
Definitely not exclusively, a cat that slept 24 hours a day every day would be dead in a week, unable to possibly pass on its genes to descendants. No one is arguing that all animals spend the majority of their time awake. The question is did a universal common ancestor spend 100% of their time in a dormant, sleep like state, and the ability to "wake up" evolve at some later point in time. The answer is no.
By animal standards, plants are permanently dormant. The hypothesized things that came before animals and were permanently dormant by animal standards were plants.
And also plants diverged from a common ancestor with animals, animals didn't evolve from plants. Animals (and all other eukaryotes) probably evolved from something more like the Archaea, which don't seem to have anything resembling sleep.
Yeah. Perhaps animals are the first organisms that developed the ability to be awake, not the first that developed the ability to sleep.
By the way, even Cnidaria (jellyfish etc) exhibit sleep-wake cycles [1]. They don't have a brain, but they do have a nervous system. Maybe the first animal with nervous system (a common ancestor of Cnidaria and Bilateria) was the first to have a sleep-wake cycle.
I don't understand the current research on mitochondria, but it sounds as if sleep has to do with how neurons work.
That's actually very interesting. The most convincing explanation for also I've heard is it's just a result of living in a planet that is cold and dark half of the time. It makes sense to use that time to recharge. I wonder how much sunlight would factor in for something like a jellyfish.
Sleep is still detectable via CPU load, so I added a thread that checks for load and runs some critical cleanup processes when it drops below a preset threshold.
