This sort of makes sense, as unnecessary movement drains energy. It seems counterintuitive, then, that sleep has survived for so long, but the forces pushing fo

This sort of makes sense, as unnecessary movement drains energy. It seems counterintuitive, then, that sleep has survived for so long, but the forces pushing for it must be strong. It does seem rather coincidental that we sleep for 7-9 hours, which is the majority of the dark time, during which wakefulness would only expend energy with little gain (thinking of apes instead of modern humans)