[ELI5] Why can other species sleep with their heads up but we can’t?

Question

[ELI5] Why can other species sleep with their heads up but we can’t?

In: Biology

Answer 1

It pretty much boils down to evolution. For tens of thousands of years, we haven’t had to worry about it as much with basic shelter building. Prey animals they been well getting preyed apon at night for maybe hundreds of thousands of years. We burn less energy not having to do that and therefore have an advantage in survival, given we are safe at night