It's been suggestes that humans might naturally prefer biphasic sleep when removed from artificial light. https://en.m.wikipedia.org/wiki/Biphasic_and_polyphas

It's been suggestes that humans might naturally prefer biphasic sleep when removed from artificial light. https://en.m.wikipedia.org/wiki/Biphasic_and_polyphasic_sleep https://en.m.wikipedia.org/wiki/Biphasic_and_polyphasic_slee...