[toasterlovin]

We don't actually know if 1/3rd downtime is a requirement. For most of our evolutionary history, it has not been economical to remain awake at night, so our intense sleep drive may actually be driven primarily by conservation of energy (since energy has been a major engineering constraint for all of our evolutionary history minus the last several hundred years or so). If that's the case, then with other processes may have evolved to fit themselves into our sleeping time as an optimization, but perhaps those processes could happen while we're awake if our evolutionary constraints were different.

[kgeist]

>it has not been economical to remain awake at night

Why? If you can gather fruits or hunt pray while all your competitors (or predators!) are asleep, isn't it an advantage? What about nocturnality? https://en.wikipedia.org/wiki/Nocturnality

[jjk166]

Why are your competitors and predators asleep?

At night it is harder to see food. It is harder to see predators, some of whom are in fact nocturnal. It is harder to notice visual cues and gestures from allies/kin. It is harder to navigate, both due to difficulty seeing distant landmarks and nearby obstructions, so you are more likely to get lost and/or injured. It is colder so your body has to spend more calories to keep you warm.

There are adaptations that can improve nocturnal capabilities, but these typically come with tradeoffs that make diurnal life harder. Evolution is a series of many baby steps - either you need to adapt to not sleeping while you're still at a disadvantage at night, or you need to adapt to being awake at night while you still need to sleep. Neither path seems like it would have been advantageous to our ancestors.

[adammarples]

Well we can't see can we

[seventytwo]

If it were biologically possible, other organisms would have evolved that capability. There’s some fundamental, biological reason why all animals sleep.

[toasterlovin]

Again, we don’t know that. It could easily be that the adaptations needed to operate well at night (in addition to during the day) just aren’t worth the energetic cost or they entail a large morphological compromise. The thing about evolution is it doesn’t give you its reasons.

[chuckwfinley]

Exactly, evolution also will leave things at "good enough for function". It may well be that our sleep cycle so happened to level off at "good enough" considering our other evolutionary constraints.

Definitely an area of study that seems interesting to me.

[xtracto]

There was this fad of multiphasic sleep in the early 2000.

I remember, in theory you could do sleeping for 15 minutes 6 times in 24 hours.

[interludead]

The polyphasic sleep experiments

[santanna_]

I did a polyphasic sleep cycle in college (2010's) for 6 months out of necessity and it worked really well.

The way I got it to work was by meticulously tracking my REM sleep. I would have sliding 3-4 hour windows to hit REM sleep and if I didn't, it just felt like a sluggish day, not any worse than being woken up by a fire alarm at 4am or a long thursday night.

[euroderf]

> our intense sleep drive may actually be driven primarily by conservation of energy

Or perhaps to keep us quiet and immobile, and harder to locate and eat ?