You could look at biphasic or polyphasic sleep. If it makes you feel any better, humans would apparently sleep in 2 chunks for most of history (waking up for a few hours at midnight-3am and sleeping again). As long as the total sleep duration is adequate, some research shows that it's not necessary to get 8 consecutive hours.
> humans would apparently sleep in 2 chunks for most of history (waking up for a few hours at midnight-3am and sleeping again)
I have read this claim for decades now, but I have trouble believing it. To me, a claim about pre-civilization human behavior doesn't have a whole lot of merit unless it can be explained as being evolutionarily advantageous to mammals in general or humans in particular. Humans are diurnal and I can't imagine a scenario in which "wasting" a few hour of potential sleep is worth it somehow in the middle of the night when it's dark and there's nothing to do anyway.
The closest I can come is that _maybe_ some small percentage of early humans were polyphasic sleepers, which benefited the tribe by watching out for a pack of hungry wolves or enemy tribe attacking in the middle of the night or whatever.
