comment: >
  
  This doesn’t really make sense. By your logic, couldn’t someone just argue that we’ve actually evolved so greatly on other levels (technologically, engineering, etc) that we now have the luxury of being totally vulnerable while we sleep because we’ve created safety systems like enclosed domiciles? Isn’t that just a perfect example of evolution?
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  Like other mammals, humans live in groups and have security systems that protect the group.  Like a locked door.  Or 500 years ago, someone in the village or tribe that slept in the day and was awake at night. >
  
  That's probably why some people have a intrinsic tendency to wake up really early while others are the opposite. Diversity within a group probably worked as some sort of defence mechanism. Nowadays we are just lazy when we have a hard time going to sleep early/waking up early. :) >
  
  There is indeed a theory proposed a number of years ago in psychology and sociology which speculates that the reason older people tend to have more trouble sleeping and require less sleep per night has to do with exactly this. The idea being that older people are more likely to nap during the day when the younger portion of  the village would be busy doing tasks and chores that older people are less able to do. Then, at night, older people are more easily awakened by external threats like animals, invaders, or impending natural disasters and would then go about rousing the people to counter or escape the threat. 
  They also pointed out men tend to wake more easily to when disturbed by sounds with bass and tend to lose more high frequency hearing range as they age. Women tend to be more readily awakened by higher pitch sounds like a baby crying, and tend to lose more in the lower frequency ranges as they age. 
  I wish I could provide a source on this but I do not remember which podcast I was listening to at the time. I can only say that it was around 2018 and I was doing a ton of research on sleep disorders, sleep apnea, PAP therapies, and generally all things having to do with sleep hygiene when I came across a podcast with a research scientist talking about it from a historical/evolutionary perspective. I've never been able to find a paper about this online despite having looked again just now. 
  It seems very plausible though, considering that, in the past, many generations often lived with each other and this would have niched the roles somewhat. >
  
  My personal take away from this is that humans weren't meant to survive alone but as part of a community. >
  
  The only thing we have going for us that isn't related to living in groups is our ability to chase anything to death >
  
  Yeah, that was a real insight when I learned that. Plus points for making one prey's skin into a water carrying pouch to better chase down the next prey. >
  
  That's knowledge passed down from being social >
  
  Many animals have existed much longer than humans and are the same way. Yet to see a dog or wolf or bear spray acid from its ass as a defense mechanism and remain asleep after. Because that self-defense mechanism is called "waking up" >
  
  Except people like me; I’ll fight without waking up. >
  
  In the ancient past, it was called a watch. Each watch was 3 hours then rotated to the next person on watch.  But you're right though. We sleep more soundly in modern times. >
  
  Reminds me of ftxs in the army. Or missions in general >
  
  Bro why you getting down voted LMAO >
  
  Idk it's true.
  Someone stays up guarding SI, or even in garrison they watch the building aka staff duty or cq. Then they get a rest day after.