My question is, if sleeping less (with FNSS) offers so much advantage, why haven't we all evolved to sleep less with FNSS? If a mutation offers a distinct advantage, natural selection will force us to adopt it sooner or later.
There is a theory that sleeping more hours was not a determining factor in survival [1]. Homo sapiens mitigated sleeping on the ground as a risk by sleeping in groups.
> However, too much deep sleep is dangerous. REM is the stage of sleep in which we experience dreams, so our muscles become paralyzed to avoid acting out these dreams. In his “social sleep hypothesis,” Samson suggests that our ancestors mitigated the risk of deep sleep by sleeping in large groups with at least one person on guard.
> “Human camps are like a snail’s shell. They can pick it up and move it around with them,” Samson says. Our ancestral hunter-gatherers might have slept in groups of 15 to 20 around a campfire, taking turns staying awake and watching over the others.
Humans already sleep far less than other mammals, so that seems to be the case. It also might be evidence that attempting to get by with less has costs. Sleep debt has a range of troubling symptoms including psychosis, so risks involved in experimentation are significant.
